First time posting on reddit and on mobile, so sorry in advance for any issues. Long post

Basicly the situation goes like this : I am staying over with my brother and his family, our mother is also living with them. Today I was asked to give my nephew some medicine because he is sick. I went to their medicine cabinet and find what looks like a bottle of medicine. 
Being a responsible adult, and wanting to find the correct dosage, I looked at the label and saw that the medicine was homeopathic. Being that im really against sudoscience because its so dangerouse and predatory, I get upset and start to look for another medicine thinking they might have bought it by miatake. Nope, all their children's medicine is homeopathic, but ironicly not their adult medicine.
Because they had so much non homeopathic meds for themselves I decided to be more casual about my aproach when confronting them. I immediately went out to the living room where they were at and asked them if they knew what homeopathy was.
My brother and his gf (mostly his gf) essentialy told me that they wanted to raise their child on alternative medicine and that in addition they didnt vaccinate my nephew either...
All of the sudden a few things clicked in my head that made me enraged
1. They dont use homeopathy exclusively for themselves
2. My nephew nearly died from the flu last year, he had to go in an ambulance one night after a severe seizure due to the severity of the flu, I now believe this was because he wasn not vaccinated

I imediatly raised my voice and told them that stuff was not backed by science and that it was completely dangerouse to not have him vaccinated, after arguing I called them hypocrites for not using that type of medicine for themselves and having had vaccines as children. We got into a shouting match, I was visibly upset and raised my voice, and started using profanity.
They got upset and called me closed minded, said they weren't hypocrates because it is already to late for them to start to be clean or some bullshit. 
This is when our mother got in and called me a jerk, told me college had radicalized me and closed my eyes and how dare I come into my brothers home and critisize him. At this point I relised somehow my mother had also been turned to this shit, she told me she also stopped using her medications for her illnesses and moved to natural medicine, and told me how great it has been for her. 
I was so shocked and angry, and my entire family there told me I was a jerk, not open minded and that I didnt have my nephews best intrest just a need to feel superior because I go to college. They basicly all turned on me. I left by just saying they were all insane and that it would be their fault if anything ever happened to my nephew, god forbid, and finished by saying that they were the ones responsible for his condition last year( I may have said this with a few more curse words) and then stormed out.
Im now gone from there and feeling terrible about this, especially since I did this so close to the holidays and maybe blew this out of proportion, so AITA ?