If this is all true, you'd be better off without him OP. You're looking for true love and he's just looking for a nanny with a fanny, from the sounds of it. Of course you're going to be disappointed in that situation.
You can apply for a refund on the campervans tax, tell them it's SORN, then after you've got your refund tell him that too so he can go tax it again himself. Call up the insurance and tell them you're no longer willing to pay it with immediate effect. Then call your bank and tell them to block any payments coming out from the insurance company (you'll need the name of it for them). Then tell your boyfriend he needs to contact the insurance to reinstate payments from himself or take out new insurance.
He's not a partner OP, you're not in this together, you don't live together and you don't part-own a campervan. He's just a live-out boyfriend who's spun you a story, sold you a dream of camping holidays and in doing so he's got you to pay his tax and insurance on the campervan he solely owns. Stop being a pushover.
Is it an abusive relationship? The sulking isn't good. You sound so ground down, woe-is-me and lacking in self esteem OP.
I can't believe you're in your 50s. From the way you write I'd have put you at early 20s, emotionally immature and from a chaotic background with dysfunctional parents, someone who's yet to fully grow up and figure out how the world works and learn to recognise shitty men who aren't worth bothering with.
I feel like he's pretending to be what you want in a life partner so you stick around, but that he'll never actually be that man and you'll spend your entire life disappointed and feeling second best if you stay with him.