Can I be forced to pay for my daughter’s college?

My daughter just finished up her first semester in college at George Mason University here in Fairfax. She partied all the time and did terribly in school, barely missed failing out. In my separation agreement with her mother, I agreed to pay for 4 years of college, but that was under the assumption that she was going to apply herself. I’m not paying tens of thousands of dollars for her to sit around drinking and having fun with her friends. Is there any way I can get out of that clause of the separation agreement? Also, her mother is doing nothing to rectify this situation and just says our daughter will grow out of the partying stage. Even though my daughter is in college, is there anything I can do to get custody of her and make her come live with me under my rules if she does want to stay in school?