I can't decide I'm scared?

i am 16 and live in nevada. my dad lives in michigan with my 25 year old step mom. my dad left when i was about 3 when i was going through chemotherapy and fighting cancer. my dad and i have never been super close or anything and my mom has always been there 4 me, but now my bro moved out in febuary and i have been put in the middle of my mom and brother fighting. my mom is addicted to smoking weed and her emaciated body leads me to believe she is doing other drugs but i have no proof. my dad has said i am more than welcome to move in with him and start my junior year there but i am not sure what i should do and i am so so so lost stressed and nervous. i am to the point where i barely eat and i get sick just thinking about it but i cant stop please someone help me!!!!!!!!