TIFU by sleeping with a married woman

Yeah this was actually last week. I don't know what to do, I just need this off my chest.

It started out as a normal beer with friends, last Friday. We always go to the same pub to start, sometimes stay there all night. It's a cool pub which only plays heavy rock/metal. If you're sick of chart music or pop it's a great spot to hang out and play pool. We got there, I paid for a round of drinks for us and we started out the night smashing Metallica and Sabbath on the jukebox.

The friends I'm with have other friends there who I'm less acquainted with, but I know of their faces and vaguely their names. So as we're drinking and picking songs, a few girls walk over to my pals with the usual "heyyy how you doing" etc. The woman I'm talking about is one of these friends, and introduced herself to me. She was nice, tomboyish, quite good looking and I had fun chatting with her. She asked me to put Bruno Mars on in this pub - first red flag.

A few more drinks into the night, we get bored of the jukebox and head out to the beer garden to smoke and chat some more. I immediately noticed wherever I sat she would pick the seat next to me, and sort of lean in. She would get really close. I thought okay cool she seems interested in me, maybe this could be a good night. I told her I was staying with my buddy and his girlfriend at their place since my car was already there. She's good friends with my buddy's girlfriend, so she blagged staying over there too and we all got a taxi back together.

We got back and continued drinking/partying together. We were all really drunk and the flirting was less awkward at this point. She was cuddling into me on a sofa whilst we all chatted. At some point, around 3am, she pulls her phone out and says "wonder what the hubby's upto" and I was like wait... "What? You have a husband?" To which she replied "yeah for 10 years".

This was just a stepping stone in the fuck up.

I asked her to come outside and chat about it, saying like wtf are we doing? She explained the relationship had been dying for years, they live separately and it's not even a real relationship anymore. I don't know what I thought about this, but I kept the flirting up as this calmed me a little bit about the situation.

Eventually we end up in bed together and had sex. It was awful, I don't think we were compatible in that regard but I tried my best none the less. I didn't wanna be labelled a shit shag or whatever idk.

So I wake up the next day pretty early and leave saying thanks for hanging out etc but I gotta get home. I thought ok mistake has been made but we'll just leave it at that, afterall, her marriage isn't going well and will inevitably end.

And here comes the fuck up

She found and message me on Facebook, something along the lines of "would gladly let you throw me around again xxx" and I clicked on her profile. My fuckin heart dropped. I instantly recognised the pictures of her husband, and they looked so happy together (at least online they did).

The husband is someone I used to smoke weed with and chill with a lot, through secondhand friends. We had the same dealer and would chill at the dealers house for a couple. This happened weekly for nearly a year or two, but we never really knew each other past that. All I can say about this dude is he is really a great person and I enjoyed his company. Sometimes he would talk about how his wife is being crazy and distant with him and it made him sad.

I fucked up guys. I need to tell him but I don't want to hurt anyone, but it's beyond that now. I followed my cock and this is where it's landed me. Fml

TL;Dr

I slept with a woman knowing she has a husband. I thought it was a failing marriage, but turns out I used to hang out with the husband and he's a really great guy. I'd never met the wife before this night. Now I don't know what the fuck to do