Ex wife wants to move back into family home

Hi, my partner is having a nightmare time with his ex wife and her varying demands - I hope someone can shed some light for me as he is getting more and more stressed by the day.

Basically 6 months ago his ex wife moved out of the family home with the children and took on a rented place(no warning was given and for 3-4 months her and the childrens whereabouts were unknown). My partner has been left paying the mortgage in full - overpaying as the bank will not let him reduce to interest only unless his ex wife agrees - he does not live there but rents a small flat to try and get a bit of sanctuary where she doesn't know how to find him. His wife has heard that he has done the house up (as she trashed it before leaving making holes in walls and all sorts) and has contacted his letting agent who he has for his business to state under no circumstances is he to rent out the house (he was hoping to try to get the mortgage partly covered as its £900 a month due to the overpayment). She said to the agent since she has heard it has been redecorated she might move back in. Can she do this? A lot of the things she says and does are to try to get a response out of him (despite she being the one to have affairs, initiate the divorce and allowing zero contact with his children for 6 months). It just seems impossible and I'm hoping this isnt another one where the courts will favour the crazy ex wife but I suspect it might be as she has the children with her.

They are still married. The house is marital property and is unoccupied. Why do you think she shouldn't be allowed to move back in?

No they are actually divorced and not just "seperated". The finances have not been settled and against legal advise she signed the divorce without getting the money sorted.

I think it is unfair of her to saddle him with £900 a month debt as she is refusing to pay anything towards the mortgage, and by not letting the property be rented so he can stop her putting him into debt. (which is crazy as the more debt this creates the worse it is for her for the financial settlement)
He is happy to pay for his children but not to have the P taken by his ex wife. At the moment she is angry that he is not paying her more child maintenance even though he is paying what the courts have ordered ­base­d on his income... and with £900 a month tied up on a mortgage that is slowly putting him into debt its not possible to offer her more help with raising the children by subsidising her rent/bills

OK... still, if they have no financial agreement and are joint owners of the house then she has the right to live there. They are jointly and severally responsible for paying the mortgage.

He should sort out the finances from his marriage ASAP. This is exactly the kind of problem that occurs if you don't. In the meantime I would recommend that he move back into the house and stop renting his flat.

As Cookie says, when you are faced with an unpredictable (ex) spouse , your only sensible course of action is to go to Court and sort it out once and for all.
But may I ask you first whether the property is in joint names ? It may well be, of course, that it is, and if so she has the right to move back.
But if not - well, it could matter. Can you resolve this for me.
Another piece of advice ; if your partner signed a fixed term renting contract and moves out he could still be liable for the rent for the remainder of the term. Just be careful.
LMM

Thanks Cookie2

The financials are a must for sorting - will start work on that today.

actual divorce is final - at least one part is done.
child access has been ended for the sake of the children (had been pursuing access to them but it was getting so messy and distressing for the children we have stopped that now and are hoping in the future when she calms down she may put the childrens desire to see their dad above her own desire to make him miserable)

Not sure about moving into the property - he doesn't want to live there and she cannot afford the bills on it (even with the mortgage paid) so I'm not sure how she could live there - as I said, it may be her trying to get a reaction out of him again.