I slept with my friends ex, but I like him

I kissed this guy about a year an a bit ago stayed over his but nothing happened (because i didn't want it too), he was friends with some of my friends so I saw him often and started liking him a bit.

My house mate then started sleeping with him and then went out with him (for just under a year). I was a bit upset at the time but soon got over it because I didn't want to come in between anything.

My housemate and I had drifted even before this boy and our friendship was very distant whilst they were together.

My friendship with him strengthened and we got on really well. I always knew I kind of liked him but it subsided whilst they were together.

They broke up 8 months ago. She was gutted and called him all the time after nights out etc to check he wasn't with any girls and would pull him up on getting with others. (apparently she is still pretty hung up on him)

I moved out about 2 months ago and have only seen her at our friend group meet ups and haven't really spoken since.

Him and I were at a house party and I was very drunk and he showed up. We were together most of the night just making jokes and hanging out (but this isn't unusual).
Then when we went to bed we ended up having sex. I stopped it because I started to feel bad. Then in the morning we had sex again. It was nice, I enjoyed it. He told me after he has always fancied me and I agreed.

A few people know about it but I don't know if they're going to tell her. He doesn't want to because he thinks it will crush her.

I feel so guilty. I want to tell her because I think thats the right thing and I wouldn't be able to look at her when we all meet up. I also worry about it coming out and then that makes me dishonest and deceptive. I also don't want to loose him as a friend.

Part of me doesn't think its that big of a deal and another is ridden with guilt.
Some of my friends say telling her is not worth the repercussion because she will go crazy, others say its right to tell her and maybe it will help her get over him.

I don't know what to do!!

I kissed this guy about a year an a bit ago stayed over his but nothing happened (because i didn't want it too), he was friends with some of my friends so I saw him often and started liking him a bit.

My house mate then started sleeping with him and then went out with him (for just under a year). I was a bit upset at the time but soon got over it because I didn't want to come in between anything.

My housemate and I had drifted even before this boy and our friendship was very distant whilst they were together.

My friendship with him strengthened and we got on really well. I always knew I kind of liked him but it subsided whilst they were together.

They broke up 8 months ago. She was gutted and called him all the time after nights out etc to check he wasn't with any girls and would pull him up on getting with others. (apparently she is still pretty hung up on him)

I moved out about 2 months ago and have only seen her at our friend group meet ups and haven't really spoken since.

Him and I were at a house party and I was very drunk and he showed up. We were together most of the night just making jokes and hanging out (but this isn't unusual).
Then when we went to bed we ended up having sex. I stopped it because I started to feel bad. Then in the morning we had sex again. It was nice, I enjoyed it. He told me after he has always fancied me and I agreed.

A few people know about it but I don't know if they're going to tell her. He doesn't want to because he thinks it will crush her.

I feel so guilty. I want to tell her because I think thats the right thing and I wouldn't be able to look at her when we all meet up. I also worry about it coming out and then that makes me dishonest and deceptive. I also don't want to loose him as a friend.

Part of me doesn't think its that big of a deal and another is ridden with guilt.
Some of my friends say telling her is not worth the repercussion because she will go crazy, others say its right to tell her and maybe it will help her get over him.

I don't know what to do!!