Not my child?? what to do?

my ex- girl friend that i haven't seen for almost a year, came to my house with a baby and said that the kid is mine. I'm only 23 , but told her that i would pay child support and take care of him "IF" he is mine.

so i have been buying him things and taking care of him and being a dad to him for the past month, i finally decided to get a DNA test and found out that he is not mine. I have all ways said that if the kid is not mine , i don't want nothing to do with my ex and the baby and that both of them can get out of my life.

the problem is that i have gotten so close to him, that in my heart he is my son. He stops crying when i pick him up, and loves to fall asleep when i hold him close to my chest and in my arms.

My EX is the girls of my dreams that came to early. i cheated on her, and she left, and we dont really get alone, but she is in love with me and wants to be with me, but i don't want to be in a relationship right now, i want to be single and enjoy my life. i don't want to take care of a kid that's not mine, but this situation is so hard i don't know what to do???? Her parents have a lot of money and she really just wanted me to be the dad because she knew that i would be a good dad. she even told me that i don't have to give any money, but she just wants me to be there for him.

her parents would love to see me and her together, and have tried everything to make it happened. they have offered to buy us a house, a new car, pay my debt off, every thing.

i have found out that the father raped and almost killed her. I dont want this kid to grow up as mistake. i have seen a pic of the father (he's in jail for another rap and murder) , and it's scary how much me and him look a like. same hieght, color skin, hair , eyes, just not the mental.

my heart is telling me that i need to be the dad to this kid, but my pride is telling me that i'm young and shouldn't be taking care of some kid that'ss not mine??