angel, i am so sorry...i all too well understand the nightmare of a child in pain
i do know that for our children, we have to be strong...when we are with them, we have to show that we are good
as long as we are good, they have their rock
i would not send the letter
however, i would not even think about divorce until your child is on stable ground
everything between the two of you needs to be put aside right now she comes first
you need to work together on this to get her in a better place
but i will tell you this, your h will feel nothing but resentful if you guilt him into coming back my h was the one who suggested us spending more nights together for our son and i can tell you, the first morning that he was here was horrible
perhaps just suggest that your issues need to take a back seat right now to your daughters
you need to do it gently and make him feel like part of the decision