OMG - absolutely feel sad, you are entitled to. But don't stay there!
You're already solo parenting and if this is "indicative" it doesn't sound like you're getting a whole lot of positives from him. Leaving might well be a weight off your shoulders, and don't say "no friends, no family etc.". You might well have a bunch of people around you who think he's a total twat and that you're lovely, but you just don't know it yet and they're too polite to say. You got 9 people immediately jump in to boost you up and tell you you're not being unreasonable from one post a few hours ago!
20 years of this sounds really grinding, are you prepared for 20 more? On top of childcare, school drop off, clubs, sports, birthday parties, etc.? And I bet that with his attitude you have no couple things to look forward to. No date nights, no birthday surprises, no Friday flowers or sexy texts.
Think about what you want and start writing it down. A house closer to friends and family? A job/more flexibility/a promotion? Imagine your perfect life and write down even the little things you want (your own tea in bed?). Then gather what you need to make it happen.
Bank statements (his and joint)
Mortage docs/tenancy agreement
(Kids) Birth certificates and passports
(His) Payslips and pension statements
EntitledTo website estimate of the financial support you'd get
A safe place to put these things
Once you have these things, you can start to write down your questions and seek out a solicitor for a free half hour to go over what you'd be entitled to in a divorce. Check up on rightsofwomen.org.uk/get-advice/ if you're in the UK and arm yourself with information.
If he's up in bed with his cuppa he'll not even notice that little old ground down you has a gameplan. And keep posting on here for advice.