I was actually going to post today that the change in her behavior might be because she has given up, not cheating.
Just because she has no hope NOW does not mean she will not be willing to do counseling in a few months or a year.
She is partially depressed because of the relationship. She might separate from you to heal from that and then be interested, but you are going up against a lot to work against depression and any marriage issues at the same time.
I don't know about the cheating end now. It might be she is cheating and has justified it with this. Otherwise, she has turned a corner and give up.
Again, she might not have any hope or interest NOW, but your job is to do whats right. It will be a LONG road.
2 Thessalonians 3:13
And as for you, brothers and sisters, never tire of doing what is good.
If she decides to separate, let her and continue to pursue the relationship. Don't smother or be needy towards her. If she doesn't want to contact or talk to you, don't. Build yourself up as a Godly man. Strong, stable, and doing whats right and good.
Do not underestimate the depression. Its not possible for her to love or see hope in the depression if its caused by the marriage.
12 “Even now,” declares the LORD,
“return to me with all your heart,
with fasting and weeping and mourning.”
13 Rend your heart
and not your garments.
Return to the LORD your God,
for he is gracious and compassionate,
slow to anger and abounding in love,
and he relents from sending calamity.
14 Who knows? He may turn and relent
and leave behind a blessing—
grain offerings and drink offerings
for the LORD your God.
Get in and talk to your pastor ASAP with or without her. Ask her to join you, but go alone if she does not. Perhaps, go separately.
The next few months or years could be very difficult. Your marriage is in full crisis mode. Prepare yourself, get into Gods word, lead a Godly life, read christian marriage books, and pray hard.
At this time, you can very much affect what is going to happen, but any REAL and full healing on her end is up to her and God. The same goes for you.