Perhaps its time to sit down with your mom and get it all out on the table. Tell her you & BF hit a rough patch that you, in an emotional state over-shared about, but have sorted it out, and you want to try again with him. That is the truth right?
Remember too, that sometimes people on the outside see things that we can't. Address the Red Flags and then be thankful that someone else has eyes on this with you. Let your mom know that you are being cautious and aware as you move back into this and that you need her not to judge right now. This person means a lot to you and is worth the effort you are giving it.

But do all that with as much love as you can muster. She only wants what is best for you.

Good Luck & Best Wishes