1FM,
I know exactly what you mean about the kids. My grandmother told me, when my eldest was born, that after you have a child, your heart travels outside your body the rest of your life. I think you can probably relate to that sentiment.
My kids have had to deal with a lot of garbage as a result of my first M breaking up. Their dad and I have joint custody - 6 months with me, 6 months with him, and visitation for the non-currently-custodial parent. Sounds all peachy and involved, doesn't it? Then xH moved 1 state away and then 1000 mi. away. I tried to get the order changed and couldn't. So for 7 years my kids transferred from one school to another in the middle of the school year, until they were of an age that they could decide for themselves where they wanted to live. Their dad hasn't lived in the same school system more than 3 years at a stretch. They have really gotten yanked around. There are down sides to that, especially for my eldest who is quiet, retiring, and slow to make friends.
There is also an upside. They have lived in a large city, they have lived in the country and had a horse and roped goats. They have seen tumbleweeds and oil derricks. They have been to concerts and museums and the theatre. They appreciate luxuries but don't judge those less fortunate.
So, what's my point?
It sounds like your children are set up for this next year, at least. And I would think their current needs will be considered in any settlement, so perhaps their school etc. won't have to change. Even if it does, they will find themselves exposed to new situations and they will learn from it. As long as they have your love, your involvement, and your support, they truly will be fine. The tough lessons are what make us deeper and richer as adults.
I remember thinking my kids' lives were going to be ruined forever. And yes, they cried during transition times because they were homesick for the home they were leaving. But they are intelligent, healthy, well-loved children. They have a wealth of talents and interests. They pick their friends wisely. They talk to me about their lives. Things are going well for us. Things will go well for you, too. It seems so big now, but I'd wager it's bigger to you than it is to them.