I feel uneasy and unsure about this guy.... Any good advice?

So he asked me out, I said yes, but then I broke up with him at the end of the day cause I heard he doesn't haves reputation bc he used to do drugs, gets in trouble, etc. Everyone says he's not guy u should get involved in, but then I found out that he's been really sad bc he really still likes me and wants to be with me..... He also has been trying t make a point of saying he has quit drugs avd has been keeping his grades up for me bc he knows that those things r important to me. He's also been texting me a lot and being really seet and flirty. I have no idea wat to do bc I feel I didnt give him a fair chance, but I'm not sure. Someone help!!!