Cathy,
My heart goes out to you. I can understand and feel what you are going through. The tragedy is that that usually your own children aren't aware of your pain, or worse just don't care.
I'm one who writes down my thoughts when they are running full power. I have learned, though, it's best to sleep a night before sending them. I've saved myself lots of trouble that way. Let your daughter wait a day (no harm in that), and reread your mail as if you were a stranger to the situation. Try to put yourself in your daughters place, and see how she would read it. I'm a very emotional person, and my husband has taught me that the fewer the words; the better it's said.
Yes, of course go and help your daughter. It gives you a good chance to bond again. When with her, just be carefree and happy,…and try not to bring up any problems. Believe me, that will make you the winner between you and MIL.
Hannelore