I can think of two women I know, off the top of my head, who are Leos and have similar problems to you: exactly what you describe. Bad marriages to selfish, disrespectful men, bending over backwards to make it work, and in at least one case, constantly feeling that she gets backlash if she tries to stand up for herself.
One of those women did leave her selfish, disrespectful husband, spent several years as a single mother fighting a drawn out custody battle, and now has a much better husband and interesting adult children.
What causes backlash is you acting in a way contrary to others' expectations. It sounds like you respond to that backlash by retreating. As it is, you have people trained to see you as the self sacrificing, non-assertive person who will help them no matter how badly they treat you. Whenever you start to change and assert yourself more, people in your life react by saying, "No, don't change!" and you acquiesce and stop changing. Which makes the same thing happen again each time you get fed up and decide to assert yourself.
But what if you didn't back down? What if you responded to your husband's insults and tantrums with, "You're right, Husband, I'm a b___ who doesn't support you. I won't (fix your dinner, clean up your mess, drive you to work, go to your family event, etc.)"? What if you waited out the ensuing bigger tantrum and stood your ground? (And called the police if the tantrum escalated into violence.)
If you can imagine being more assertive, you can do it. What's missing is the follow through.
Your current situation isn't something you're fated to because of your sun sign. It isn't even a situation that Leo or Aries people are immune to (though they might find such a situation even more frustrating than you do, if they are in it). It may be that your Libran desire for harmony has turned into "keep the peace at all costs," which makes you do what you do--but that's a pitfall of Libra, not its fate. The solution is to swing the balance of the scales back in favor of yourself. Even if that means you have to seriously fight to do it.