God! Don't we all sound like shrivelled up man-haters? Nothing could be further from the truth, but it's definitely got a dodgy feel to it.
Definitely don't open a joint account and definitely opt for legal advice regarding your inheritance.
Other than that, if you want to go ahead and marry somebody that said he'd never marry you, that's up to you, but reading between the lines, I think the dosh is the real attraction. Sorry!
If he hasn't committed to you in 7 years, why not go and blow the lot on a gorgeous toyboy instead, lol.