Planning on sleeping with my best friends ex

They weren't really bf/gf but more like friends with benefits. When she started to develop feelings he broke up with her. I've been friends with both for a few years and have always been attracted to him. We've been chatting recently and are planning to get together to hang out. I know sex is a real possibility. Am I doing the wrong thing? Should I put my feeling aside and go for it? It's just sex, right?

Well I don't think it would be wrong for you to have sex with him exactly but what reason would you be doing it for? Love or just passion/lust. Most people pass having sex off as nothing serious these days but in actual fact it can be a pretty serious matter. You said your friend developed feelings for him which can complicate things, if you really have feelings for him and maybe consider him as a future bf not just a one night stand, go for it. But If it's just a fling for you a one night stand don't do it, respect your friends feelings and wait for a guy you really do love or could see him returning those feelings. Jst be careful who you sleep with because it can have a big impact on your life and your relationship with your friends, I'm sure your friend will understand if you really do like him but of not I think she'd be pretty upset which will endanger your friendship