Sometimes you do have to ask for help. If it isn't a family member, it could be someone from church to help with your Mom. As far as asking Gabe about Marc, do it. He is his father. Please stop being afraid of the end result. He left before and you know what...the world didn't stop revolving and you certainly grew stronger.
I think you need to talk to him about this without bring emotion into it. "Gabe, I need you to help with Marc, getting him to xyz. It would help me and mean a great deal." If you aren't ready to take this "situation" to a deeper level then you aren't but at least be open to telling him what you need.
hugs, kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory