He is asking sorry for what? For his mother’s attitude and thinking? Or all the wrong which he has done. What I feel that he has some other gf which has left him now. Since now he is empty handed so he messaged you.
Yes, as per his past behavior he may change his color. So beware of him. If you become weak now and reply him then again you have to go through all the pain. So as a friend I suggest you that ignore him. I know this pain is very bad. So please don’t involve again.
Your caring friend.