Have you ever fallen in love with someone who isn't your type?

I'd suggest you seek individual counseling. If you have been uncomfortable for over 20 years, it may have less to do with being married to him and more to do with what is going on with you. Somewhere along the line you need to talk to him and tell him how you feel. Couples counseling may also be in order. I don't buy the "you marry once, period" excuse for staying for 20 years. You stay because on some level there is something comfortable about being there. If you were really that miserable and were independent (financially) you would have left long ago.