We all know why you are exhausted!
"The conversation " needs having but I'd include your son-in-law who may be an ally -after all he is the only one who respects your space.
Before the conversation take a look at what you have agreed to do and what you feel obliged to do and what you actually do.
There are lots of jobs in a house - are you trying to "run" it? How much "family" stuff are you responsible for?
Things to look at that I don't think you have already mentioned:
Shopping, cooking, clearing the table, loading/unloading dishwasher, collecting laundry from round the house, sorting, washing, pegging out, ironing, cleaning - hoovering, windows, dusting, tidying up after children, bins and recycling, homework supervision, bathtime, sorting out activities (music books/gym wear/ballet gear or whatever... responsibility in itself is wearing.
You say:
I bought this house with my DD and SIL, and pay half the mortgage, taxes, utilities etc.
If you are doing all this and living in a fraction of the property then it sounds to me as though they should be able to finance a gardener (for example). Otherwise the mortgage wouldn't have been approved.
I don't know about your income but if I had surplus income I would pay for a gardener. Or - if usually you like gardening I'd get a cleaner or pay for after-school clubs.
Something has to give as you have no "mental down time".
You will be what "gives" if you don't resolve some of this.
Good luck. 
PS. As someone upthread said you need time away from this house.
Take your daughter's advice. Join a gym and go swimming which will make your spirits lift. Find one (like mine) with an older clientele and you will make friends (or at least friendly relationships) with them as I have done.
Mine is attached to a hotel. I see the same people there regularly. The "gym" side is not as big or as modern as the ones a young person would choose. ... just an idea.
You may prefer an arts club or something like knit and natter... anything to get some respite.
HRT - Starting for the first time at age 66.
Soops kitchen, a place of reflection, refuge and at times revelry.


