This must be really upsetting for you - It struck me, that as well as letting you look like 'the bad guy' , for turning down the latest loan request, he is also sitting back and looking like 'the good guy' , at your expense- because I feel as though as far as his friend's concerned- your lovely husband arranged for him to be given a van and lent £2000- but it came out of your money!
With giving the money for a van- I can't help wondering-did you feel pressured into it? If your husband hadn't suggested it, is it something that it would have occurred to you, to want do? If it hadn't been suggested, either by your husband or the friend, would you have chosen, at that point in your life , to give that much money to charity, or to a friend, and if you might have, is he ever the one you would have chosen?
I know you said the £1,500 has gone now because it was a gift-and as far as the friend is concerned ,of course it has- a gift is a gift (unless its given under duress or undue pressure)- but didn't you say it was supposed to be a gift from both of you, and it just came out of your account, because it was easier to send the money from that? In which case , if you were giving it from both of you, shouldn't your husband have put half, out of any personal money or income of his? So maybe, as regards the van- your husband owes you £750- so it's from you equally. (though depending if he nagged/guilted pressured you in to it, maybe he really should cover all or nearly all of it)
The debt of £2000- which looks like is going to be difficult to get back-should probably be totally covered by your husband-it's his dodgy
friend. At the very least, he should be responsible, from any private money or income of his- he should at least split the damage with you-so your husband should give you at least £1000, if not the whole £2000. (That's if you can't get it back from the friend.)
It's not nice that he's saying harpy mode etc-that not nice calling you names -and it's a bit gaslighting and trying to make you feel you're in the wrong-when actually you are the injured party. You're not being a 'harpy' to mention you mind people not being honest with you and about you- that's a reasonable complaint.
From what you've said , and for want of a better remedy- I'd be inclined to get at least £1,750 going into your account -either from the joint, or any separate account your husband has- just on principle .
I can also see why you'd be annoyed by him saying wife says 'no',when he hadn't asked you-it's not honest, and it's a cheek -making you sound like the 'mean one' , when you've given this man most of your inheritance!
I would do a bit of googling , to be honest - being flash or careless with other people's money can be connected with sociopathy or narcissism, and do a bit of reading on it-just to check your husband isn't hitting lots of descriptors for either of those conditions and you just haven't previously realized. Also, maybe look up things like economic abuse in domestic relationships.
Look after yourself, anyway and don't let him be dismissive of you, he ought to be apologetic to you, since his friend has gone cantering off with your money, like Dick Turpin , in a van . (A van that you paid for, to add insult to injury!)