I’m sorry that you and your daughter, and your wife and subsequent children - are going through this OP. It has to be so painful. It’s one of the reasons that I could not practice family law for very long. Too close to my heart.
The thing that gets lost in some of these situations (besides the kids who are stuck in the middle which is horrible) is that - even if you and your former wife were still married - there’s a decent chance that you might disagree over how this college search and selection process would happen (or you might disagree on other parenting issues).
Even among married couples you see “magical thinking” about how, exactly, college is going to be paid for. On top of it all you have other children to consider, but saying that to your first child may make the situation worse.
If I were you I’d try to find a competent, reasonable attorney to help me sort through this. I would just want someone to give me some ideas on what the options are. I would not necessarily sign a big retainer to gear up for a battle.
Wishing you and your family peace and clarity.