I need advice really bad!?

there is this guy that is 21 at this time and I am 18 I had a crush on when i was 11 but he was dating some one who is basically my cousin but not blood wise and they broke up when I was 14 and me and him continued talking because we have both always liked to hang out together but then when I was 15 some stuff ended up happening between us and we it was like we were together with out the actual label behind every ones back from when I was 15 up until like a little over a year ago and we stopped talking at all because my basic cousin found out some how and she was threatening to call the cops on him for me only being 17 at the time. But like 3 months ago we got in contact again over the Internet and now it is like a replay again... I thought I had finally moved on from him but now I realize I am still completely in love with this guy we have never had a real big fight and we get along grate... And I don't know what to do, I want to be with him but I know that means that my Basic cousin her mom and sister will hate me and not talk to me any more. But at the same time that could be a good thing because they are nothing but drama... What would you guys do? Should I continue seeing him or Just cut all contact off? OPINIONS???I need advice really bad!?
Forget about everyone else. It's not like youre taking anything from them. If he's single, and you like each other, then you guys should be together. Seriously wtf, please just do what you wantI need advice really bad!?
I would take it slow and see if he's worth it. Date him for a while and just don't put it out there for your cousin to see if you don't want her to.