DOesn't sound like you screwed up, sounds like H did.
Part time sounds good and what is best. The blind child analogy is a good one and could be said to the school if needed, I think.
Remember, as it gets closer and closer to the decision making, your H is going to try to manipulate you. ONly talk to him about kid issues. WHen he tries to talk more, you say that the lawyers can work that out. Your posts lately seem very controlling on the part of your stbxh. He is trying to manipulate you.
