I'm sleeping with my ex who is my partners best friend but my ex is now dating someone else is it bad I still want him.

Yes, you need to respect his relationship even if he doesn't... and you should also probably stop sleeping around with an ex... nothing good can come from that.

You don't know what you want but you seem to take whatever you can get, so its not bad having feelings, but what is bad, is what you are doing about it.

Do you really think guys don't talk to each other about how best to screw you dumb females that think their feelings are the same as yours?

If you do, then you have real life, and BS all screwed up! Sorry to be harsh but good sex is not love romance or anything but a fun time to most guys, and best friends look out for each other. Remember that as you bop back, and forth between best friends.