Great advice from catlovingdoctor.
As someone with severe IBD, I know how rotten you're feeling right now. Dehydration will make you feel so much worse.
They're not the best isotonic solutions out there but if you can't stomach rehydration salts (and please, if you haven't tried them yet - do!) then opt for a sports drink like Lucozade Sport.
When your salts get out of whack with the fluid intake, it makes dehydration worse.
If you start to experience cramping in your legs over the weekend (sign of low salts), I'd suggest heading to A&E for rehydration.
Keep sipping water, or crushed ice, or an ice lolly, but don't feel bad about going to A&E if you're not keeping your fluids up.
I have to say, I've never had vomiting as a result of IBd so I'm with your gp that a bug or food poisoning is most likely. You're panicking because you feel so ill, which is normal.
Also, dehydration makes nausea worse. If you can keep some liquid down it will make a difference.
I'm sorry your husband is being such a dick :(