how would I go through with dating him?

okay so there this boy and him name is zack I met him becuase his dad was dating my sister. so when I would go and visit my sister well I would see my sisters boyfriend randy because they lived together. so I eventaully met his son who is my age (zack) and at first I wouldnt talk to him becuase I didnt really liike him . But after a few times seeing him I would like talk to him. and I would go to my sister’s and stay the night like every friday so I would see him but we started talking and stuff so I guess we became friends? but I would lie to him and tell him that I had a boyfriend and that other guys wanted to date me. I was only doing that becuase I wanted to seem “cool” becuase I knew that he kind of liked me. so time went buy and my sister and her boyfriend broke up. my sisters boyfriend randy is now in jail . and zack lives with his mom and my sister jen is in a relationship with some one else. so I didnt see zack for a long time. but I eventually created a a social site and I found him on there and added him! we started talking all the way through like last summer. and then he told me how he really liked me and stuff . and like I didnt really like him like that becuase I know that your not supposed to judge someone by there looks but hes over weight so hes fat I mean that could have changed since I last seen him but that bothers me. I mean hes kind of cute but the whole being over weight thing grosses me out. and then I started being mean to him on the computer and he got mean a lil while after that after I had stopped being mean and said that I was ugly and that he only talked to me becuase he felt bad for me then he blocked me on mysppace and time went by and I made another a social site and sent him a friend request and he excepted it and we started talking again and he said that he was basicly sorry and that he didnt mean what he said so I forgave him I guess he was just having a bad day that day . but now hes like asking me for my number and calling me sexy and then he asked me if I had a boyfriend well I decided to be honest and told him that I do not have a boyfriend . and then he was all like well do you wanna go out and I mean I have never had a boyfriend , so I’ve never kissed anyone. but he thinks I have.. and im not about to just come clean and tell him that I never dated anyone becuase that would just make him get mad at me or something. so I’ve just decided that since it was a while back that I told him I was dating someone that from this point I will be honest. but im kind of desperate I mean it would be nice to have one of thoses dates like 7/31/09 or whatever haha. and it would be cool to finally get my first kiss. but thats wrong to only date someone for that reason . but when he asked me to go out I said ha sure but we’ve been talking on a social site. so I guess were going to plan a time to meet somewhere. I havent seen him in a long time. but I have really missed him & always like wonder what it would be like to kiss him and stuff. so do I like him? I don’t know.- do I want a relationship? yeaaah. -but maybe I do wanna date him im just soo confused but when I think of dating him I always think of the whole him being fat thing. help me please I need some advice! and plus I dont wanna tell him that I dont wanna date him becuase peoplr have told me that before and it hurts!