Help please !!!129300;

Your only legal obligation is to pay child maintenance. The following calculator will allow you to see how much you'd need to pay: https://www.gov.uk/calculate-your-child-maintenance

Try explaining to your ex why you can't sustain the amount you have been, rather than merely stating that you are paying (I suspect) more than you are legally obliged to. Your ex may reduce access unless you can sort this amicably. Sadly the CMS does not prevent the parent with care from reducing contact to get more maintenance.

If your ex wants to stay there...they will have to pay for it. I hate the expectation some people have!

You need to see a solicitor who can then advise you based on your specific situation.
However, the aim in any financial split is to come to a settlement which is fair to both of you, taking into account all the circumstances and the needs of both parties and of the children.
You have a reasonable need for somewhere to live and to have the children visit, so it is reasonable that you should be able to rent somewhere.
It would be unusual for you to continue to pay towards bills or a house you are not it. It is more common to contribute to a mortgage in the short term, until a settlement is reached, but not common to do so after an order is made.

You mention your ex is a student - when does she graduate, and what is her earning capacity likely to be when she does? It may be appropriate for you to pay spousal maintenance a strictly limited time, say 1 - 2 years, but it is likely that the amount would have to be reduced from what you currently pay to allow you to afford somewhere to live, too.

Is the £220 half the mortgage + 1/2 bills? How much is the mortgage element of that? As a short term measure, it might make sense to look at reducing the amount you pay to 50% of the mortgage payment, paid directly to the lender, and to take your name off all other bills (if it's still on them)