This will be my only update, and I'm only posting it due to the amount of support I've gotten as well as the numerous requests to do so. I didn't expect the response I got and I've unfortunately seen it referenced on other subreddits, so I'm choosing to confront it. Most of you were right. Congratulations.
I read through all of your replies and spoke to friends, and stewed for a day. My wife stuck to her story, apologized for making me uncomfortable and assured me it wouldn't happen again. Cocksucker decided to leave a handwritten note in the mailbox specifically apologizing as well. I still didn't feel better, and the consensus was that I should speak to my neighbor's wife, who we're going to call Sally, so that's what I did.
Watched my neighbor leave for work, then called my MIL to come take my wife for a lunch and a girls date so she could get out of the house. I left as usual for work, called off again and went to stay with a friend. Got a text from my wife around noon telling me she was with MIL and would be back by dinner. Went home and knocked on Sally's door.
Cocksucker decided to tell Sally I kicked him out and caused a scene about not wanting either of them speaking to us anymore because I was pissed about him "helping" my wife. Come to find out both Sally and cocksucker have been going over to my house while I was away busy for the past few weeks as my wife had approached her and asked if they would be willing to lend a hand with chores she could no longer do alone. Sometimes Sally went over and did small tasks or just hung out, sometimes both, sometimes just cocksucker.
Wife told her I knew and was fine with it, and that's why she was confused when her husband told her his bullshit about me being mad. She showed me where she texted my wife (has her number, not mine) to clarify and ask if she was welcome over and my wife hasn't replied, and since I don't often see Sally or socialize with them she just assumed her husband was telling the truth. She also admitted that she noticed cocksucker and my wife becoming "fast friends" and figured it was due to the pregnancy, but thought it was his way of dealing with their own inability to have kids so she wrote it off. I told her what I walked in on. I told her about the tools, which ended up being bullshit too.
Came to the same conclusions. Both cried. Both hugged for the first time. Both took turns denying and accepting and talking each other down. Took a walk around the block together and conspired. She planned to call cocksucker at work and say that my wife messaged her confessing to the two of them having an affair, and seeing what happened.
Went back to my friend's. Started having major panic attacks thinking I fucked up, I was about to ruin my marriage, worrying I might be wrong. Bit later and I get a call from my wife screaming at me to find a way to leave work and come home. So I go home. Cocksucker called her telling her what Sally told him. She (his wife) told me I was crazy, I was a piece of shit, that she was considering leaving me, everything. Having a panic attack thinking I just ruined my entire life over nothing while also trying to calm her down for the baby's sake. Impulsively told her that if she was leaving, I'd still be requesting a DNA test.
And that's when it all came down. Entire tone changed. Pleading, begging, apologizing, hyperventilating, holding me. Asking me how I found out while denying anything happened. I told her it'd be ok and asked if she'd talk to me if we went for a drive. She agreed. Took us to a parking lot and we talked, told her if there was any chance of anything happening she needed to tell me what was happening because I already knew a lot. She'd fucked cocksucker a handful of times before she was pregnant. Our baby might not be ours. Cocksucker had been coming by and doing daddy duties once in a blue moon "in case it's his". They haven't slept together in months. She said we could move away, that it's ours no matter what, that he had manipulated her. Admitted she lied to Sally to justify cocksucker going over for daddy duties. I asked her if she'd stay with MIL for a few days while I calmed down. She agreed, took her home, packed up some stuff and dropped her off.
I've cleaned out my essentials and I'm in a friend's basement. Friend called her on my behalf and told her that if the baby is mine I'll be dealing with it, if it isn't it's on her, but either way I'll be filing for divorce. My friends took my phone from me and deleted my social media. She's been calling my friends, friends told her to fuck off. I spoke to my boss and he's been very understanding. Last I heard from Sally, cocksucker hadn't been home and stopped responding to her calls and texts. I have nothing left. In less than a week my life has fallen apart. The only thing keeping me here is the small chance that baby is mine. I have nothing else. I woke up today disappointed I woke up at all. I've never felt this alone, and I haven't accepted any of it yet. I'm praying for the first time in my life that I can stop feeling this way and find strength.
TL;DR There's your update. For those of you who took the time to reach out, I've been reading your messages even if I didn't respond and I'm incredibly grateful, they're much needed positivity. For those of you who took the time to mock me or accuse me of lying, ask yourselves just how much you think I give a fuck about your approval. Value those close to you and what you have before it's gone