is this fixable?

Let me start out by explaining my story:
Me and my now ex boyfriend met and started dating over a year ago. he is 10 years older than me. he was my first everything, he took my virginity and became my first love. he was my best friend and my only friend.

Half way through our relationship, i started finding pictures of him and this lady all over facebook and twitter. i confronted him about it and he always had some type of excuse. during this time he also started disappearing for days at a time without answering his phone, he would claim he was taking care of his kids that he had from a previous marriage which i already knew.

things started to get better untill a few weeks ago when he was sleeping at my place. his phone kept going off and so i eventually answered it. on the other end this lady explained to me how they had been dating for a year (the same length as us) and how 2 months ago she just had his baby.

he heard me talking to her and threw a huge fit which included him stealing my phone and posting rude things all over my facebook and twitter.

the lady called me a few days later to tell me more about how almost every weekend he was down there with her, how they would leave town together and she finished off by saying "if you still want to be with him you can just know im not going anywhere"

a few days later he called to give me back my phone and that he wanted to talk. he began to tell me how he lied to me because he loved me and he knew i would break up with him if he told the truth. he told me he feels nothing towards her and how she trapped him into having a baby with him because she was older and lonely.

i told him i want nothing to do with him but my actions show different, since that day i let him sleep over once but told him that was the last time and that i need to move on.

just last night he showed up at my house at 3 in the morning crying and begging me to take him back. saying he was so sorry and that he made a mistake and hes only human. saying he wants to marry me and everything and i ended up letting him stay the night again.

im soooooooo confused right now because i love him soo much but what he did to me hurts soo bad. i could never look at his child and forget what he did to me but im so unhappy without him. it hurts so bad that im considering moving because i know there is no way in the world that i would be able to get over this kind of pain living here where everything reminds me of him.

i dont know if i should take him back or move on. this is my first break up, i need some advice