One of the things that keeps so many in a bad marriage is the fear how we are going to cope in the future.
His thread to not pay the school fees in order to keep you in your place (e.g. the marital home) is appalling, quite frankly.
Divorce is about splitting the assets and the child care in an appropriate manner. It is not about who is the shittier spouse and why.
Him continuing to pay the school fees will come down to a) what you negotiate and b) whether he can afford to following the split. He may have no option about that as the changes to the children's lives must be minimised insofar as it's possible. The kid's welfare comes first, second and third in divorce. Then his needs, then your needs, and finally :your/his wants/wants a distant last.
You don't say how old you both are, or the length of your marriage (including period of co-habitation pre-marriage). But all these things have a huge bearing on the settlement in your divorce.
It's worth you going and have a chat with a solicitor to get an idea of what your life would be like post-divorce - everyone's divorce is different so don't imagine just because your neighbour's Aunt Sally got left with nothing, but Uncle Bob was taken to the cleaners, means that's the fact.
Making an appointment to help you decide to stay or go, is not the same as filing for divorce.