Have the confidence to know that you're step mother is wrong in this matter. Also know that you won't convince her, but that's not your issue.. it's likely a reflection of an issue she has.
Worry about yourself - a big part of me getting better in my depression and anxiety has been caring about myself and not worrying about how it fits in with other people like my family and sisters. While we all love each other, there is something in our dysfunction where my family likes me being the
identified patient and I got tired of living that role.
Cosigned.
As the
Identified Patient in my family, it took a long time to realize that no matter what logic or rationale or emotional appeals I presented, they were nevertheless entrenched in the
need for me to be sick or wrong, and would actively sabotage or undermine any attempts I made to seek help or improve. Whether they could articulate it or not, the entire toxic family dynamic was clearly reaping benefits from me being unwell, and they were heavily invested in the narrative that I was lazy/stupid/willfully disobedient.
When I started getting better, it gave the lie to their perceptions of me, and made them feel deeply insecure about their own issues and how their unaddressed mental health challenges/lack of support contributed to my former difficulties. It was easier for them to try and put me back in my place than to cultivate the awareness to confront their own problems.
They would literally withhold my medications, refuse to help me get to counseling appointments or sabotage my own efforts to do so, and if they found out that such-and-such thing triggered me to the extent of self-harm or substance abuse (for example, I'm autistic and changes in routine or surprise house guests are very difficult to handle), they'd make a point to do it over and over.
Once my Dad called my counselor demanding to be given transcripts of I was saying in my appointments. He didn't want to know
how I was doing -- he wanted to know
what I was saying. I think that says a lot about their priorities regarding my wellbeing. Luckily I was over 18 and the counselor refused to divulge any information whatsoever. Apparently he called her a "meddling cunt" and "quack bitch" and other expletives. My next appointment began with her saying, "So, your Dad seems like a real nasty piece of work..."
Anyway, the upshot of all this is that mental health is THE top priority, and I've learned that I can't have people in my personal life who don't, won't, or can't recognize that. If someone would rather see me unemployed, bleeding, drunk, high, or dead than getting help, then they. Gotta. GO. They're a genuine threat to my sanity, and I've put too much hard work into that to compromise it for anyone.
This may or may not be easier said than done in your situation, but if you have the ability to cut people out of your life who don't support your wellbeing, do it and don't look back. We accept the love we think we deserve, and you deserve to be loved in a healthy manner that nurtures your best self to fruition. You do NOT deserve to be belittled, degraded, or undermined in your attempts to recognize and treat your legitimate challenges.
