House sale

[Anne36012]

I’ve never posted on here before so not even sure if anyone can help me but I thought I’d ask if anyone is an expert in this region and I don’t have to pay more solicitors bills.
In 2013 my partner (not married) walked out on me and my son ( was having an affair with co worker) I continued to live in our house which is in joint names and have been paying the mortgage solely ever since. He has since shacked up with the girl he left me for and they have a child together. He now wants to sell the house as he has been renting. This I completely understand and have no intention of trying to make things awkward but at the same time I want to be able to provide a nice home for my son now 8 (& myself)
We bought the house in 2007 for £205000 when he left in 2013 the house was valued at around £175-180k.
Today it’s worth around £220-225k.
I am now in the process of trying to buy him out but because he will not help me with child care I am really limited as to jobs because I can’t work shifts etc. So my earnings are minimum.
Now I’m trying to get him to settle on a figure for a buy out. Would any profits made since he left and I continued to pay the mortgage be mine?
So if I sold on today’s value at say 220 minus the mortgage amount then split 50/50 (even though I’ve kept up payments on my own) we would both walk away with roughly 75k each. But if this was calculate on the value of house when he left his 50% would only be roughly 53k and I could continue to live in the house. I am aware that I would then in theory get more out of it but without sounding bitter because he doesn’t have to worry about childcare he has had free reign to peruse his career and earns my annual salary in about 6weeks so that £50k plus his salary would allow him to get a bloody nice house where as I am not quite in the same position.
So essentially when working out the division would I base this on the house value when he left or today’s value? (Legally speaking this is not morally)
Sorry for waffling but I really am eager to get sorted.
Any advice would be greatly appreciated x

To add to this.
We are remnants in common. He put £50k into house I put £10k and signed a declaration of trust to stipulate this.
I was made redundant due to branch closure in May and have now started a new job but with a lesser salary as I have had to start at bottom again. I cannot get enough borrowing to buy him out on my new wage, however I have seen a mortgage advisor and worked out how much extra I need to earn and with another part time job I can manage, but this is impossible in the 6 weeks holiday without any help with looking after son so I can’t do anything until September (he does have him regularly, every Sunday afternoon to be precise but will not deviate from this) , he is now threatening me with a court order and said his solicitor has stated a CCJ needs to be lodged against me first. I work in a bank so cannot have bad debts against me and this would make it near impossible to get a mortgage if he does follow through.
Can you get a CCJ against someone for a mortgage?
TIA

*tennants in common 🙄

This is such a complex issue you do need to talk this through with a solicitor esp as ex partner has one. Hopefully one will see this thread and give you some advice. Best of luck

If you can afford to buy him out (bearing in mind the extra interest he has according to the deed of trust) a court would expect you to do so. However it appears that you can't do that. He may struggle to force a sale given the purpose of buying the property was to have a home for the child and the family. You could apply under Schedule 1 of the Children act 1989 for an order putting the property in trust to enable you to remain in the property until your child finishes secondary education. See a solicitor.