It's very common that only the mother comes to IEP meeting, etc unfortunately. We divide by strengths. I am better at advocating-being polite, yet assertive, and knowing the lingo and needs and being tenacious. My husband is better about taking to sports practice and allowing our son to face highs and lows rather than wanting to march onto the court and tell off any kid who is rude to mine (haven't done it, but have wanted to

. I do make sure he comes to any neurodevelopmental pediatrician appointments so he understands these are issues that must be addressed and he doesn't slip into denial.
As others said, if he's a good father otherwise than is huge. If you are burned out, figure out a division of labor that focuses on strengths. If he sucks at IEP meetings and dreads them and you don't like them, but know how to get the job done, then do it. If you hate helping your kid with homework and you husband is more patient, have him do that.
Also, yes to your own therapist. If you truly feel you cannot negotiate a division of labor that works and you are drowning do couples therapy. My experience though was it was easier to figure it out on our own. The couples therapist had no clue what it was like raising a kid with HFA. I think she just googled it.