His parents are funding most of it, so what do they think? Are they agreeable to funding a 350+ person wedding? Like you, they may also be way happier spending the money to help you guys get a house of your own.

And if your fiancé wants the big wedding, you shouldn't be the only one planning the big wedding - especially when it's contributing to your already severe anxiety.

From what you've written, it sounds like your fiancé doesn't have a lot of empathy for your mental health status or what you want. If you're both recent college graduates, I assume you're also quite young (though I could be wrong) and not many people who are in their early twenties can finance a 350+ person wedding. I'm in my early thirties and I wouldn't be doing it either, especially if I was in the hole by $70,000 and lived at home still. I think his priorities are off, but those vary a lot from person to person and change with age.

Personally, I'd feel guilty asking for my Dad and future in-laws to fund a huge wedding as well. If I were in your situation, I'd be having a serious conversation about what is realistic and practical given your circumstances - financially and regarding your mental health.