This girl I've been seeing is cool but I don't trust her because she jumped into bed with me, and still talks to her ex, and has a lot of guy friends.

You are not supposed to trust her. How old are you an how long have you been seeing her, and what's the nature of this dating relationship??

If you don't trust her, why are you seeing her? That makes no sense. Maybe she has a lot of friends with benefits, and you are just one of them. Maybe she is a playa.

You tell me.