I feel for you and your situation. You both are in my prayers. I have been through a divorce and have since become engaged again and each relationship has posed unique issues. My ex-wife could not stop spending money. I tried for years to make it work and more years to make it stop. I tried everything I could think of and it finally came down to me letting her know that I loved her and I wanted to make our relationship work but I simply could not continue to be in a relationship with her if those behaviors continues. Three strikes later she was out.
With your situation, she has come to you and told you about, what I assume, is a previously undisclosed sexual proclivity. Aside from the interest in Deist beliefs, it seems to me that your biggest problem is that this behaviour of hers has come to your attention after you were married. Unfortunately you cannot change that. A few years in you get a surprise dropped on you in the form of what you percieve to be a flaw in your mate. You likely feel shocked, hurt, betrayed, angry and a lot of other things. When learning of this you, in your words, forbid it.
Now, I know this is likely to get some folks dander up, however, fully consider this from her perspective in a more abstract or emotional point of view. There is something that she has done, does or likes to do. I think it is safe to assume that she was sufficiently worried or embarrased about it with regard to you that she kept it hidden for some time. She likely even abstained for your benefit. Time passes and she continues to have the urge to engage in this behavior and because she has in the past it is not a curiosity but a reality for her. She comes to a point that the urge has become strong enough that she has had to work up the courage to talk to you about something she has not been honest about. When she tells you, her husband, she is met with all of the above emotions and your ultimate action is to FORBID her from engaging in it. I understand I am making a lot of assumption but considering your absolute reaction to this, I am not surprised that she decided to reach out to somone she thought would be more understanding.
We are all fond of saying here that a sin is a sin and there are no degrees of severity. What if she had confessed to you that she had a previous drug addiction and was feeling weak or like she wanted to do it again? What if she told you that she had a habit of shoplifting before she met you and recently had done it again? Would your reaction have been different?
We as humans are interesting creatures. Why does sex matter so much more than the rest. I had many people assume that adultery was involved in my divorce. It was never an issue. That being said, I have also thought and said well at least she was not running around on me. Even I took comfort in the fact she did not go there but is that right?
In the end, I can only tell you what has worked for me since then. I met and fell head over heels for a wonderful woman whom I will marry in November. It has not been all smooth sailing though. Early in our relationship I made it very clear that the most important thing to me was honesty. I told her I did not care how bad the truth seemed that to me I could deal with it. I have learned since then that it takes a great deal of trust to tell someone you love something you think may hurt them. We have both worked very hard to earn that trust with each other. Our personal mantra has become "No matter what". What is behind that is an acknowledgement that neither of us are perfect and a promise that no matter what happens or how we may stumble that we can always go to the other with the truth and without fear of losing our relationship.
That being said, you also must set boundaries. Boundaries are personal to you and are vastly different to forbiding someone else to do something. You may say to her "I love you with all my heart and I want to find a way to make this work, however, I can't accept how this makes me feel and I can't be in a relationship with you if you continue to ___________." As someone said before, express your patience but also make it clear that the patience has limits." You can love the sinner and hate the sin. If you are in love with an alchoholic you are in love with an alchoholic. Love them for who they are as Christ loves us.
Christ gives us a great example of love. He loves us unconditionally, he tells us the life we should live but he understands we will fail but his love does not. His forgiveness is free and unlimited for those that seek it. Yes, the bible and Jesus tell us many things about how we should and should not live our lives. In spite of that, he tells us that all we need to be with him for eternity is to believe in him and love him. He says this in full knowledge of our sinful nature. When we sin and we are guilty or hurting because of it, Christ wants us to come to him. He wants to love us sins and all.
Look at your wife through Christ's eyes and love her. I know some of the things she has done have hurt you. Christ paid heavy price for us and his love for us even though he knew we would continue to sin. If you really want to make it work with her, go to her, give her a huge hug and tell her you love her and how much. Tell her how you have been feeling about what she has done and then appologise for your reaction. Tell her that you want to talk about her issue and listen. Ask her why she likes it, how it makes her feel, why she did not feel comfortable talking to you about it, and why she still finds it appealing. You might gain some insight into why this plagues her. Once you feel like you really understand why she is attracted to this then take a closer look and if it is not abjectly opposed to your values or faith and if it is possible, then try doing it with her. If it is one of those obvious no no's then try asking her how she would feel if you did the same. If those are not appropriate then at least try and discern what feelings this behavior gives her and try to find something more appropriate to fit the bill. If it is possible to recreate the situation with the two of you by role playing a bit then by all means give it a shot. Tell her how you feel about her reaching out to her ex but also tell her that you accept your part in the why she did it. Tell her that you want to be her answer and safe place for everything.
When my then girlfriend and now fiancee confessed an indescretion to me it hurt like nobodies business. I held to my promise of no matter what and the first thing I told her was that and that I still loved her and wanted to be with her. In the end, I understand why she did it even if I do not approve and she understands the impact it had on me. I thanked her and loved her for her honesty and her deep trust in me with the hard truth. I never once forbid her from doing it or doing it again. More than a year later I asked her if she had ever felt tempted again. Her answer was that she had thoughts sometimes but never felt really tempted because she understood the impact it had on me and that she never wanted to do it again. I believe that our love is so strong because neither of us judge each other and we accept and love each other for who we are.
I see a lot all over this board about being firm and standing fast, putting your foot down and making your wife submit to your god given authority. I also see just as many posts from men who complain of being brow beaten by bossy and overbearing women. Personally, I would just say to try and love your wife like Christ loves you both.
If anyone of you have read this far, thank you and I am sorry to be so wordy.
SD I think you can save your marriage if you want to. If you do, as much as it may hurt, losen your grip a bit and love her even harder.
Peace and blessings to you brother.