Aww @Soupe du jour Im so sorry that you have an infestation. My fiance's mum has one too but it doesnt sound half as bad. But even that is hard to deal with, catching them, disposing of them. I couldnt handle it. Plus the faeces, yuck! Its so difficult! If its as bad as your husband is saying, maybe not a suit, but rubber gloves, a covid visor and overshoes might help appease him? Or is it the suit or nothing? I can understand his suggestion based on what youve said before about his OCD. Maybe exploring other suggestions a little more could help?
So he feels validated and that youre taking it seriously, but maybe being a little more.... realistic? (dont use that word though, it sounds invalidating doesnt it?)

Im sorry you had an argument, but glad that you made peace!

Sending lots of positive thoughts and hugs