Communicate with your mom however will be most comfortable - phone call, email, letter - but absolutely set some ground rules before she comes for her visit.
Even though you will always be *her* child, you are no longer *a* child, so she gets no say in the decisions you make for yourself and your family.
Make it clear that the needs of your children will always come first. Always. If she gets bent out of shape, let her. Ignore her drama. Proceed with your own plans. If you want to leave and she doesn't, just go. She'll come with you or she won't. You can't control her choices. If she throws a tantrum, let her. Ignore her. It will take all the energy out of her "I'm the victim" show. Don't worry if she gets mad at you. What can she possibly do to you? You're an adult and she lives thousands of miles away.
I really feel for you. I have the same situation, only it's my MIL and she only lives 15 minutes away. I struggle with this constantly. The way I cope is to spend as little time as humanly possible with her.
I recall a time I foolishly invited her to our neighborhood festival. My two little ones were ecstatic and wanted to play in the bouncer, ride the ponies, get ice cream, you know, all the normal things kids do. My MIL spent the whole time huffing and puffing and being annoyed that she had to stand around and wait for the kids to finish these activities before we could move on to the vendor booths. I never made that mistake again, even though she is constantly trying to invite herself on our outings.
I'm a big fan of natural consequences. If you act like a spoiled diva, you will quickly find yourself alone. My MIL is far too narcissistic to understand this message, but I really don't care. But she has noticed that she is no longer invited to events with us. Don't know if she'll ever put two and two together. And don't care.
Just remember, she can get as mad as she wants at you, but it doesn't need to change how you live, the choices you make and the activities you do with your children. The shoe is on the other foot now. If she wants to stay in YOUR house, then she needs to live by YOUR rules!
Best of luck with your mom's visit.