Oh dear Kimmy, I was in that very place a few times in my life-- I feel for you-- it's so hard. I literally felt like I was a pressure cooker and could "blow" at any moment if I didn't get some down time.
I mean this in a supportive way-- where is your "partner" through all of this? Wouldn't he understand and allow you to have some time to yourself-- maybe even one weekend afternoon a week or one evening a week...... -- not meaning he's not supportive-- but I'm sure you would help him if he needed something. Or maybe your daughters could take turns with little man......
Everyone needs some private time and/or down time. I'm concerned for you-- it's such a rough place to be. If I can help in any way-- please let me know.
Kimmy---