Your presence isn't going to 'fix them' and make everything better. They'll still be the miserable people they have been and you'll be miserable around them.
Save yourself. Have NO guilt. YOU didn't make your parents the way they are, so you have NOTHING to feel guilty about.
On the other hand if you give these people time out of your life and make yourself and your husband miserable that's something YOU chose to do, and can legitimately have guilt about.
You can choose to make your life and your husband's life better by getting the 'toxic family' out of your lives. Then you'll have absolutely nothing to be guilty about because you will have done the right thing for you and your family, (your family meaning your husband).
Your parents from what I've read haven't earned your loyalty, in fact they've earned your fear. Yes, they fed and clothed you, but people do the same for pets. You owe them nothing at this point.
I grew up with an alcoholic father who's now nearly on his death bed. He wasn't quite as abusive as what you describe, but he was abusive enough that I learned to distance myself from him to save myself. For years before he went into a rest home our relationship was a 'telephone relationship' only. With my father, if you're not in his presence, he doesn't seem to get enraged with you and the conversations are actually pleasant. That's the ONLY way I found to have a civil relationship with him.
But there's still a certain amount of guilt that makes no logical sense. I feel I "should" go up and see him in the home, but on the other hand the old bastard didn't even bother to come down for my wedding.
Fight the guilt. Ask yourself which is worse, getting abused by your parents and having them abuse your husband, or feeling a little guilt, (that you shouldn't logically feel), and keeping your distance?
I'm glad you managed to get out of that miserable situation and find a husband that gives you the respect and love you deserve! As they say, the best revenge is to live well.