To think his undiagnosed ADHD is too much for me?

[NotGreatExpectations]

My husband of 10 years has always been difficult.
We have 4 children under 8 so are very much ‘in the trenches’ in terms of parenting and this past year has been the hardest in our relationship.
I work in education and know for certain my husband would be diagnosed with ADHD if he actually had the guts to see a GP but he refuses.
There are so many things he does that make me unhappy (I am getting my ducks in a row and think I can financially leave within a year) but wanted to know if I’m being unreasonable for not supporting him more, especially given my job and what I know about these conditions. It’s very easy to advise others on how to support their kids but much harder to do this myself when physically living with this adult.
some of the things he does:
-becomes obsessed with things such as motorbikes, a film/tv series and will be fixated on this for a few weeks. Will either research motorbikes, buy one etc or binge watch this film/tv series over and over. Most recently this was paranormal so spent hours researching ghosts and binge watching YouTube clips, reading online forums. Has done this before with UFOs, vintage cars, a state in America, piercings etc. makes no difference what the ‘thing’ is, he just becomes obsessive.
-will promise to do a chore/errand and then never follow through on this meaning I’m constantly pissed off or disappointed
-struggles to have serious chats so our rows get swept under the carpet as he will avoid eye contact or walk away or get angry
-have very angry outbursts and be defensive if I highlight something he hasn’t done. Then will calm down a few minutes later and apologise profusely but as he does this so often I struggle to forgive him immediately so then he gets annoyed at me not forgiving straight away and the argument continues.
-when we socialise he goes to extreme but either having to get really drunk and loud/cocky or he will be sat very quiet and introvert if sober, and simply cannot communicate. If we have people over he will isolate himself and watch TV (which is very rude, but not his intention) and only relax when they go.

There are more behaviours but these are the first few that sprung to mind!
it’s a lot to live with, especially with young kids.

My groups consist of people (including me) who were diagnosed a long time ago when you actually needed significant symptoms.

Many people diagnosed recently shouldn't have been diagnosed at all. The criteria are way too subjective.

Being a self-described "ND" is not the same as having actual autism or ADHD.

You're basically just a spicy normie.

People who have zero care needs such as yourself should not feel entitled to speak for conditions that usually result in significant impairments (such as in my case).

Saying you're just different from what society classes as the norm is unbelievably privileged, and inconsiderate to people with greater needs than yourself.

Wow that is such a sweeping statement. Why just men?

Diagnosis also gives them a get out of jail free card for shitty behaviour, so bear that in mind too

Sure there's help for relationship struggles created by ADHD/ASD to learn how to communicate better, makes some adjustments and achieve fairer balance.

where is this help available from?