How do I tell my ex I can't sleep with him anymore?

This is a perfect example of why it's usually bad to be friends after a breakup. It's too easy to get caught up in the old emotions, too easy to get tangled in his life again. You both need time to recover and heal.

I suggest you tell him that you need to not see him for a while. No conversations, no phone, no email, nothing. No contact. It's impossible to get over someone when you're still talking to them (let alone sleeping with them), it's like picking at a scab. At least for several months, have nothing to do with this guy. No contact at all.

Don't worry about sounding mean; you can say it nicely. Put your needs first. Tell him you'll still care for him and your time together, but that you need to not see him at all so that you can recover from the breakup.

do you have feelings for ur ex or not?cuz ur slping with him and you say you love him but now you have another guy that u're starting to like.its weird.right now you better judge if you want that other guy or ur ex.only then you make a move.u're making ur ex feel dirty if he knows you like someone else and yet ur slping with him