Good morning, my son and his partner spilt up in October 2103,

Good morning, my son and his partner spilt up in October 2103, they are not married and have a 6yr old daughter. They have a property which is in both names. My son moved back in with us (his parents) leaving his ex partner and daughter in the house, he felt this was the best thing to do because of his daughter. They agreed that my son would give her a lump sum of £6000.00 and she would take her name off the mortgage so that my son could keep the house. He has everything in place to do this, a new mortgage with the same mortgage company and a solicitor who has everything ready and waiting. The x partner is saying she has registered for a rent to buy property with Broadacres. She said she had a house at the end of February 2014 but this never happened and now she is saying she will have a house at the end of April 2014. My son has tried talking to her to find out it this move in April is happening but she just says she does not know. My son thinks she has no intention of moving out, so last week he moved back in and is now in half of a tiny attic bedroom to see if this action will force her to move out. He is at his witts end and I seriously fear he could end his life. My husband and I are doing our best to support him but nothing is helping. He has been paying all the bills and mortgage and even giving her £200.00 a month for his daughter since they separated and he has not been living in the house. Last month he stopped the £200.00 and told her this was going towards paying the bills. She does not work and is living in the house with everything paid for so she has the upper hand and my son does no seem to beable to do anything. Last night he spoke about not paying the mortgage and any of the bills which will leave him in serious trouble but he feels now that this is his only option. What will happen to him if he does default on the payments? I have read about a short sale or a deed in lieu are either of these an option? Also can he put the house up for sale without her consent, in other words force a sale, as this my be another option. His x partner is trying and succeeding in making his life a misery and I do not know how much more he can take. I think he will have to come back to stay with us so that we can keep an eye on him, if he does that can he then contact the utility companies and say that he is no longer living there and cancel the services? This would then mean that she would have to pay for her own services, I am sure I could then talk to him and get him to continue paying the mortgage as hopefully one day the house will be his. Any advice you could give me would be fantastic, it would be rally good to be able to tell him something positive. Denise