Replying to Step mom trippin about my weed

My dad's wife was talking about weed smoking and I openly said, "I have smoked and smoke a couple times a month." I was being honest. She then said, "Oh you'll get brain damage and your still intoxicated for days after you smoke. YOU CANT DRIVE FOR WEEKS!" She used her rich uncle as some exapmle of him smoking weed and ending up homeless. He has some other issues thats all I have to say.

I then said,"Well you drink alcohol. That can cause brain damage. especially when used in excess." She replies, "no it can't! Weed does alcohol doesn't cause brain damage"

She then avoided me for months. She won't go on vacations with me, and she whispers about me to my dad when I am in the other room and my dad then comes to me being extremely critical of little stuff like not asking him what he is doing in work. While I have only been home for 20 minutes.

Its whack. Why do people have to be so damn tense? She literally is so freaked out that she wont have her kids around me. They are 18 and 16.

Its like she is trying to keep me from being part of her family or something?