How do you tell an ex-girlfriend that you don't think being friends again is going to work?

ok I think if you two could talk about everything, you could just tell her that. But it seems that you're not like that. So I suggest talk to her less and less. And she'll get the message.

You can try and be delicate with a few different lines.

"I don't want to stay friends, because I'm afraid we'll start dating again, and I just can't do that right now."

"I'm looking to start dating again, and most girls get really nervous about a guy that is close with his ex."

"I'm sorry, but in order to get my head on straight, I need space from you. If we are friends, I'll be thinking of you instead of trying to move on and find a new girl."

Good luck!

Be honest with her. The more you bottle things up, the worse it is going to get & the messier that the 2nd "break up" will be. As long as you are polite & not nasty about it, she shouldn't get too upset over it. It could be that she feels the same way.

Delicately and as soon as possible. It's completely fine if you do not want to talk to the person again after you have dated them.

simply say....I don't think we should remain friends. tell her the truth.