@Stockgirl
I understand that you are concerned for your boys but as they are over 21, your older son will be his next of kin and if he hasn't made a will, I think the house will go to him. Could you talk to your older son and reassure yourself that he will share with his younger brother?
However, you do say that you expect your ex partner to help you financially, so clearly it's not just the worry about your younger boy that is on your mind. I don't think it's unreasonable for him to give you a lump sum-maybe a deposit for a flat-could he raise it against the house?
Would he be willing to do this? I suppose a lot hinges on how you left. You say that you did it for the altruistic reason of allowing him to have a fulfilling relationship with someone else, although I don't get the impression that he had asked you to do this.
You also mention that the menopause "gave (you) a voice. Does this mean that were arguments, hurtful things said and bad feeling?
This might make appealing to his better nature difficult and I wonder if this bad feeling has continued and could this be a factor in his decision to delay putti g you on the deeds when he previously indicated that this might be an option.
If the relationship is now bitter and he thinks your "voice" was instrumental in causing the break up, then rightly or wrongly it will be difficult to persuade him to part with money, If however, you left for purely altruistic reasons then maybe he should remember this and treat you accordingly.
Horrible though it is, you are now reliant on how positive he feels towards you.
The only other thing I can suggest is that you ask your older son to speak for you.
Good luck!