Is he just my rebound?

Me and boyfriend of almost 7 months broke up a month ago. Now I really like this other guy a lot and I know he likes me too and we both want a relationship but lately I've been avoiding it because I'm scared he might just be a rebound because I was in LOVE with my ex and then he broke my heart by taking a break just so he could have sex with his best friend( at least he had the decency to take break first) and he later planned on getting back together but I said no. I could never go back to that. I just feel like it hasn't been a very long time and I've liked this other guy before the official break up, but I didn't show it because I thought me and my boyfriend were going to get back together. Now that I know we won't, I want to give a relationship with this other guy a chance but I don't know how to tell if he's just a rebound and I want to know before i hurt him or something....