WHAT DO I DO?!

Ok so I have this ex... he is really sweet and just everything... he only thing is that I have these two friends and this is how it went let's call them... j and k.... so he started dating j and he started liking me WHILE he dated j so then a month later they break up but then get back together. Then he likes me again and then dates k for ONE day and then went to me and then we started dating... then we broke up and then he started liking j and then k and now he likes me...he's honesty like a brother to me and I sorta like him.... what should I do? I don't wanna be stuck in the pattern again!