Right making sure the kids remain safe is most important. I'm sure you will have a great feeling of peace once you get those custody papers. Sounds like maybe your Mom's nerves might be getting to her. She loves her grandkids, which is why she took them from the hell they were in an brought them to you. But she also loves AD an wants her to recover. Maybe give your Mom a break she has alot to deal with mentally, I'm sure she'll is just confused at the moment.
Your right though it is so much easier when your not having to deal with the crazy way addicts think an live. Sometimes when the phone rings an I see it's my AD I just freeze, it's like... oh no now what...it can ruin a perfectly good day just talking to her..I love her but since I can't help her it's upsetting just to talk to her.
Again I think it's great that the kids have you. Your a special person to take them in an love them.. they are lucky to have you.. glad your taking care of yourself too.