What should i do im so confused i liked this guy since 9th?

I never thought i;d see the day i would end up with this guy im now 18 its been four years.we met in april again then we hit it off so well but the nxt day i find out his x is pregnant so i juss blow iit off but cnt seem to get himm of my mind. on oct 3 i saw hiim again he told me he wanted to be with me always but just couldnt leave his gurl because he;s doesnt want her to do sumthiin stooopid about the baby.he ask me to be his gurl on the side. but i dont cuz thats just kinda ****** up but then i'm so crazy about him i want to be with hiim .ohh and get thiis their kid iis gunna be born on my b-day =D .. so i need sum advise? please help