First and foremost with what I just read, you need to focus on the children.
She left hers with you? Is there drugs involved? Definitely an A, but to leave all 4 children sounds different. Sounds like with the situation you have, you have enough to get full custody, but geez this is a new read for me.
Hang in there Friend. Some Vets will be along to help. Be patient and post again to keep it towards top.