Affair discovered

[STH17]

Just discovered my wife removed our relationship status from Facebook. I'm still "married" on it but it doesn't say to her. And hers says no relationship status to display. It hurts as much as her taking her wedding rings off (which was over a year ago). Why is it such a shock to me? It hurts so much.. I have been calling my therapist all week and she keeps advising me to not snoop or look for evidence of the affair. I just keep walking myself into being triggered like this though. I was looking at her profile because I was going to try to investigate who her AP could be by cross referencing her friends and followers with people interested the same events as her. She is going to a fashion show tomorrow which she said she was going to go to by herself, but I am convinced she is going with AP. She spent $150 on new shoes this week, saying she was getting shoes to wear to the show. She bought three pairs. I feel like she is bleeding me dry in any way possible. I used to think her spending was just because of her depression and anger at me and the way I used to question the necessity of almost all her purchases. She has spent over $2000 a month on herself the past three months, and I have kept my mouth shut about it to keep the peace and not push her away with another discussion about money that I didn't expect her to be able to have without being triggered herself. All that money she spent on herself came from student loans. My income only covers basic necessities right now. I've been wanting to have a conversation about fair use of our finances for a while now, but with the A discovery what good would that do?

Tonight I am planning on going rock climbing, something I started in Feb. as a way to get exercise, socialize (which I've never done before), give my wife space, and distract myself from my marriage problems for a couple hours by being around people who don't think I have or am trying to ruin their lives. I am afraid that leaving her alone at the house with our son, she will spend more time either talking/sexting (I have no proof of sexting, but I'm not that naive) or invite him over (for sex) while I'm gone. I'm obsessing about the sex part of the A. I'm obsessing about the A. That's what my therapist keeps trying to tell me not to do. Specifically not to snoop or investigate, because it is making it worse for myself. Whenever I start feeling better though is when I think I can handle a little investigation, then I regret it! I know I can't control my wife but this is all $hit!!!!!!!!!!!!!!!!!! So I know I shouldn't try to come home early from climbing or anything.

As so many have wondered: WHAT DO I DO!?
I don't know how I can do any of the work to save my marriage when I can't get this affair out of my head and can't stop reacting emotionally (maybe not in front of my wife, but still devastating every other part of my life and health) with every new sign of infidelity and rejection I encounter. I am so close to quitting and filing divorce myself. I know I need to stop investigating. Which means I need to just let her have her affair, let her screw whoever she wants for as long as she wants. How can I possibly work on building connection with her at the same time? She has told me repeatedly that she has only not left yet because she has a teaching job that doesn't end til the end of the month, and our son is also in preschool until the end of the month. We have no plans for school for him next year because we don't know where we will be living. I only have until July to finish my thesis, which I haven't started writing because I've been busy tending to my broken marriage. AAAAAHHHHHHH!!!!! :(:(:(