how my brothers undiagnosed autism effects me

hi so i have a brother who is 2 years older than me (we are both in our 20s). for a few years now my older sister and i have been talking about how we think said brother has undiagnosed autism (our parents always knew he was special but never had it checked out). lately i have been feeling like i am the biggest enemy in his book. if i take a joke too far he explodes and goes non verbal even if i apologize. if i correct him or disagree same reaction. if i offer help he assumes i think hes incapable of doing anything and explodes on me. my sister has tried to tell me that we have to be more patient because he is struggling still living at home meanwhile i have moved out for college and live with my best friends. my mom has even defended his outbursts by claiming he is jealous seeing us live such different lives. i guess what is making it so hard for me to be empathetic is the difference in treatment i get among others, he is never like this with our older sister. on the other hand i have a lot of pent up frustration through my parents enabling his behavior. they allow him to act like this because they know he’s different and in doing so they overlook a lot of great things i have done or accomplished just to keep him from getting upset. i could go more in depth on this but suddenly i feel guilty writing it so i am going to stop. if anyone has any advice comments or feedback i would appreciate it all thank you.