ive been married for 13 years we have 3 boys one is 12,5,and the other...

is 10 months old.we got married at a young age. when i was 16 he was 22.he has been cheating on me ever since we have been married and i never found out about it untill he told me about it.he told me that it was way more than once, he told me so many different women that i lost count.then he told that he was living with another women.i feel really bad because he would always give me different types of diseases and i thought i was the one to blame but i was confused because i have never cheated on him i have never slept with another guy.well i feel bad because he would always tell me that he cheating on me and i forgived him because he told me he would change he swore it to god and on his mother he would change but a few weeks ago he called two of the girls he used to be with and he asked me to forgive him.can anyone please tell me what to do?