I fucked up

I went over to a friends house Saturday to help him work on his truck. We got it done and started on the beer and went to whiskey. His wife joined in and the last I remember was helping her put him to bed. I woke up this morning naked on the couch with her next to me on the floor. I could tell we fucked. I panicked as my buddy has a bad temper and he is one big fucker. She was still way out of it so I got my clothes on and then decided to check on him. He was still out so I decided to get out and hope for the best.
When I went back to where she was she was sitting up looking still drunk. She just looked at me and said oh fuck and don’t tell Steve what happened. She went to the bathroom and I got in my truck and got the fuck out of there. All day I have been waiting for him to show up with a shotgun or at least a call but nothing.
Just a few minutes ago he called and said he was sorry he passed out. I told him no problem and that I just helped him to bed and took off. I didn’t tell him I fucked his wife and I know she wouldn’t say anything. I feel really guilty and still scared, he had been a friend for a long time and I was his best man and we live in a small town. Add to that if my girlfriend found out she is just as scary as he is.
Thing is I have always wanted to fuck his wife but would never have done is sober. But now since I did I wish I could remember doing it.