Should I marry this guy?

I have been with this guy for 7 years, and the relationship has been rocky at best. He did drugs and drank a lot which I don't do. But, he seems to have changed since he stopped doing all of those things. He has been going to meetings, calls me every night, and I can see that he is definitely not the person I met 7 years ago. The last 7 months have been wonderful. he has been very attentive to me and has realized (at least it seems that way) that he was wrong in the way he treated me. He seems to want to do better and make me happy, but I am having a hard time trusting him because of all the things that have happened in the past. Should I say yes?