Do you believe people can change?

Chelsea
I have an ex that I am still madly in love with. Our first relationship was far from perfect. We got together when it was a bad time for us both. We use to get high together. I've been clean for over a year. He was recently in jail for unpaid traffic tickets. Well he got out and is clean as far as I know. He came on vacation with me this last weekend with his sister and we talked and he told me that he was sorry for how he treated me, he didn't believe that anyone could love him and he sees now that I've been the only one that does truly love him. He says he wants to stay clean and get a job again and get our own place and work on his music. We had a great weekend and he was perfect with me. Yet I'm nervous about letting him back in. Should I or shouldn't I? Do people really change?