When a man comes back it's rarely because he suddenly realized he loves you. It's because KARMA arrived, and you were the safest option available. He missed how easy it was to be with you. He wants to be forgiven for shit he wasn't interested in changing when he knew he was causing you and your son pain and confusion.
His ego has taken a blow, he's scrambling now to fix what he broke. I would suspect his intentions might not be rooted in love but more in desperation. His fantasy blew up and now he is facing the consequences of his actions. Ask yourself how much he cared when he was somewhere else with someone else? If you can honestly say he appeared to not care enough to stop then what's to say he won't do it again.
Taking them back is a personal choice only you can make. Once they learn that you will forgive them, then they know you may do it again. Now he's lonely, confused and crawling back. Perhaps she cut it off. You won't know the real circumstances as he may lie to avoid admitting the truth. He likely hasn't changed, he just wants to go home where it's safe. YOU are that safety. Does he deserve that?
Maybe she didn't want to put up with him, or she realized if he did it to you he could do the same to her. Would he forgive you if the tables were turned?
My advise would be to trust your gut. I wouldn't wish this on anyone, and I took the path of forgiveness and he proceeded to do it over and over again. Each time was worse.
A man that isn't faithful is the same as being alone. Make the decision that is best for you, but do so with the mindset that your efforts may be in vain, and if he does it again, he will hide it better. You will always be looking over your shoulder waiting for it to happen again. If he's not willing to get therapy, and be 100% transparent until he earns your trust (if ever) it will be a hard road to travel for you.
You have my prayers. I 1000% understand what you are feeling.
