OP, time to face facts and move forward.
You have both essentially checked out of the relationship.
You aren’t married, your name isn’t on the deeds so you aren’t likely to be entitled to anything. Regardless of how morally wrong that is, it is the reality.
So, time to start making a plan so you can both move on and enjoy lives.
Do you work? Have you checked benefit entitlements?
Did you take time out to be the SAHP or any sort of childcare?
Did you pay towards the mortgage at all over the years? What about the bills?
Firstly I would write up my financial and emotional contribution to the relationship so it’s on paper and clearly in black and white.
I would sit down with your ex and present him with this. Present it as “we both need to leave, I should be on the deeds, if we were married I’d get this but I’ll settle for this” and ask for a fixed sum to leave.
I would also take the written down financials to a solicitor for a second opinion.
But I’d start from an amicable place and try diplomacy first.