Unless you have some valid reason to maintain a connection with these clowns (like a major inheritance and you have seen the will), I strongly urge you to sever all ties with them. Life for folks on the spectrum is hard enough without that kind of negativity. You are better off without it -- and them. Relatives or not, they are not your friends; they do not support you; and they certainly don't want to try and understand you.
If you can't completely cut them out of your life, at the very least make it clear to them they are not welcome in your home. Block their phone numbers, block their emails, unfriend them on social media, the whole nine yards. If they turn up on your doorstep and refuse to leave, call the police on them. If necessary, have them arrested for trespassing and hauled off in handcuffs. They are not your friends and you are under no obligation to treat them with more consideration than you would a total stranger.
Do not attend family gatherings where they will be present unless it cannot be avoided, like funerals and weddings; and then leave as soon as propriety and decency allow. Interact with these wastes of space as little as possible. Never meet them on their turf. Always meet them on neutral ground, and always in public, never in private. If possible, bring a true friend with you, who can extricate you from their presence if required by anything from a fictional doctor's appointment to just dragging you out of there, tossing you in the car, and driving off.
Sounds harsh? The Golden Rule says, "Do unto others as you would have them do unto you." They have done badly unto you; therefore, you do badly unto them by showing them with every action you take and every word you utter that you are meeting them as strangers, not as relatives.
You are under no obligation to be a doormat for these jackasses. Don't allow them to treat you that way. As I said, cut them out of your life as much as you can; treat them as strangers; and don't hesitate to call the police if the situation requires it. They have tried to step all over you. Stomp back!