Well if you have a joint mortgage then you are both liable for paying for it. I assume you have a house in joint names. You will have to decide between you who will remain in the house and whether you want to come to some arrangement between you as to who pays what and who buys who out. Or if you get a divorce you will have to decide on what settlement you want.
Well I do not know what his earnings are or how much equity there is in the house .... while the children are in full time education it is likely that you would not lose the house and in the event of a divorce settlement you would be awarded enough to either stay in the house or to rehome yourself and the children ... but there are a few imponderables.