My advice is plan and organize now. Figure out what you want, who goes/who stays, and what is best for you. Get a solid mind set and just do it. I am in the same boat. Children understand much more than we give them credit for. My own college student stated how proud she was for standing up on my own two feet and putting my needs first.
My situation: My spouse cheated on me for the last four years with a coworker. Even to the point of moving in with her for a month. My kids are 18, 15, and 14. My 18 yr old a Freshman in College. I was unhappy because I knew I deserved so much more from a relationship than the way he treated me. I am Happy now, living for me and enjoying life.