It sounds like your husband thinks the world (including you) owes him something because he became disabled. He is hurting you and others and doesn’t appreciate your help and support. You have stuck by him out of love and compassion. In return, he complains that you are somehow not making him happy and starts up another affair. He isn’t facing the hard truth that the only person responsible for his continued unhappiness is himself. He is not the first or the only person in the world who has had to deal with a life-altering change. Blind people can and do have satisfying, productive lives. Sightedness is not what makes a good person; character is. After six years, it’s time for him to figure out how to adjust to his new reality and stop taking his fear and anger out on you. If you haven’t already, you can tell him so.
My guess from your age is that you’ve been with your husband somewhere around 20 years. If most of that time has been good, it may be that it is worth it to try to get him into couples therapy with you to reclaim what was once a happy marriage. If it was never that great and this is just more of the same, don’t let his blindness blind you. You don’t need to put up with an unfaithful and ungrateful husband for the rest of your life.
I wish you well.