I need help.

I know that this is ultimately my decision but I just want some opinions. My boyfriend of 4 1/2 years and I broke up because we were fighting all the time and we never did anything together or really talked to each other. We have also known and dated each other since 6th grade and we are now 22. Since our break up I have found someone that I have clicked with so extremely well. He makes me smile and I'm always happy when I'm around him. He is older than I am. He's 35 and I'm 22. The only thing that is confusing is I miss my ex...a lot. I'm not sure if it's because I'm just so use to him being around for the pass 4 1/2 years or what but we lived together and I still now and again find something of his and all my feelings come rushing back. I'm scared if we got back together we would just go back to our old ways. As of right now I am single and I don't want to start a new relationship until I am 100% ready. So what do you think should I attempt it again with my ex or stay single and try with my friend when I'm ready.