@LittleCactus
I echo the poster thanking you for coming back. Many Ops just post and run. This is an important matter for you so you need all the advice you can get to help you make up your own mind.
I too have now changed my 'get married pronto' advice based on this update.
How much is the inheritance? Between 5-10K or between 20 and 40K or between 100 and 200K.
I believe it is not straightforward to get a name added on deed without you paying CGT on whatever value you will be getting. There could be other costs too.
So, STEP 1, head to a solicitor (the two of you) and clarify how much of the property you are entitled to. Insist on 50/50 if that's what you want/sound fair considering you stopped paying mortgage for a few years although intend to pump it into an extension. I am aware the childcare you have provided makes up for the 2 years you paid nothing anyway, so just look at it all as 50/50 right now. Then consider what further entitlement (if any), your inheritance entitles you to.
STEP 2
Revisit the big conversation about the things you need him to improve on and demand it is made permanent and not just to get you to marry him.
STEP 3
Discuss what you want to happen with your inheritance and if it needs to be protected. You can do this at step 1 too.
STEP 4 Decide if YOU still want to marry him. And good luck with your decision.
Advice: Once financials have been sorted and if you feel still marrying him gives you and DC better protection, just marry. Don't worry too much about 'feelings' unless you can face being intimate with him or you decide you hate him.
Comment: I have been surprised and shocked in equal measure at thousands of women marrying for practical reasons and making it work. Even those couple where the man seemed so in love, I was shocked to hear the woman had to forgo romance and romantic feelings to march him to the alter. If only women could be honest with other women. The fairy tale weddings are usually only existing in books.