in over (one's) head
Too deeply involved in or with a difficult situation, beyond the point of being able to control or cope any longer. I think I'm in over my head with Amy. She wants marriage, kids, and a house, and I'm just not ready for any of that. I've gotten in way over my head with this money laundering scheme—now the mob is threatening my family if I try to back out!
in over one's head
see under in deep, def. 2.