Do you think once a cheater always a cheater ?

So my boyfriend and now childs father cheated when i was pregnant and I just found out about it and my son is 4 months . He says he was going through a lot at the time not thinking straight and it only happened once . He excuse was we were arguing a lot back then his ex was keeping his son from him and going back and forth to court . I was working a lot not really showing any attention and lack of sex , he was bored and just being stupid playing around and fucked up. I found out because i connected his ig to my ig business page and once i noticed his personal page connected i wanted to see if he was the man he said he was faithful and good to me . He wants another chance to make things right and apologizes and don’t want to leave his family .

What’s do y’all think about the situation ?