At this moment in time, you should only worry about yourself and your son. If your husband has cheated on you, and wants to leave you, stop right there. There's nothing to save, let it be, and move on. You can't make someone want to stay with you or love you. If you can convince him to stay, aren't you cheating yourself of the truth? If he wanted to stay according to his own feelings, wouldn't that be more rewarding?

The mom situation could be quickly remedied if you could move out on your own. If you do not have a job, you can take advantage of your mother doing everything for you, and seek for one. She can take care of your son while you work and save up for a life of your own, right?

Just take things one step at a time. Have no regrets, and do the best for yourself and your son that you can.