One piece of recommendation from someone who has been down this path a bit before.
Before you make the request, make sure you get rid of your own resentment about the subject. Otherwise, you will ask for hugs, for example, and then instead of being resentful that she wasn't giving them, you will just transfer your resentment - and, for example, start resenting that you had to ask.
It's hard, but make sure you really feel compassion for her when you ask (and compassion for yourself, which is why you are asking).
I know, for my part, getting rid of the resentment while still retaining detachment and a desire to set the boundary is a hard thing to do.
Me 42, W 39, S8, S6, S2 M 11y, A & ILYBNILWY 11/08 Walking away from a bad situation.