Relationship advice?

Alright sooo, this is going to be longish.
So I've been broken up with this guy for about 6 months, we plan on being together later in life, but he has a girlfriend who he's been dating for about 4 months. So I feel like I should move on too. The first boy I like lets call him "Jessie" well he's been broken up with his girlfriend for about 2 months, and I dont know if he's over it or not. but we talk quite a bit, and flirt sometimes. we went out on a date but his ex girlfriend popped in the picture and started sending me mean text messages from his phone. He appoligies but ever sense then I dont really know if he feels that way for me. He has asked to hang out but I dont know if I'm ready to wait for the idea of him, wanting me as a girlfriend. THan the second we'll call him "Liam" hes my guy bestfriend, and hes been there for a lot, and I dont know if I have those feelings for him but I know he likes me and would be an awesome boyfriend. but I dont wanna risk not having those feelings for him. So basicly do I wait for Jessie or do I go for Liam?