TIFU by asking my sister in law the wrong question

Obligatory this didn’t all happen today, more like over the past few weeks.

(Edit- I am 18, she is 25)

For some back story, I have a lot of trauma. I don’t have friends that I trust because of this, and my SIL is one of two people that I’m comfortable talking to. I’m in a place where I feel like I’m not worth getting help. I’ve been feeling like this for a long time and I’m just getting to a place where I feel like I might be able to, but I think I just fucked it all up again.

I’m leaving for college in two days. Two weeks ago, my SIL asked me if I wanted to go out for dinner before I leave. I said yes obviously, because I want to spend time with her and my brother before I leave. For some more backstory, I got into a relationship about a month ago, and it got very serious very fast. It is making me happy, it is helping my self-esteem, and I am generally feeling better about my outlook on life and my mental health. My SIL does not approve of this relationship, because the way she found out about it was me coming home from spending a night with him. She did not shame me at the time, but now I feel like she’s judging me and I don’t know how to handle it.

Anyway, I asked her if it would be inappropriate to invite him to dinner, and she absolutely went off on me. She kept saying how she felt like I was trying to replace her and my brother with this boy that I haven’t been with very long. She keeps saying how she thinks our relationship is unhealthy and how she thinks it is “a Band-Aid over a bullet wound.” She said if he is making me feel like I need to see him the day before I leave it’s unhealthy, but it’s not him. It’s me. He’s been solid for me in the whirlwind that was the last few months (have been close friends for much longer than we’ve been together, all that really changed was the sex), and I want to see him. He is not pressuring me.

I don’t think this is fair. She might be right, but I am happier than I have been in a long time. I was in an abusive relationship for eight months, and this relationship started very soon after I ended it. So, I guess I can understand why she’s worried, but I am happy and I feel like she should be supporting me rather than trying to tear me down.

My mental health has been shit for a while, my grandparents are both dying (cancer and Parkinson’s disease), my mom is an alcoholic, and I’m having a hard time with the fact that I’m leaving my brother to deal with all this. I’m also scared of how my mom will spiral when I’m not there to watch her. There’s also a lot of pressure on me as a first generation college student, and it’s starting to get to me.

SIL Started berating me for not trying to get mental health help, but what she doesn’t seem to understand is that you have to feel like you’re more help before you can actually get it, and like I said, I haven’t felt that way in a long time. There’s also the fact that my mom is a narcissist and is preventing me from getting help, even though I’m an adult (checking my bank account, not allowing me to go through her insurance, etc.). I don’t know what to do. I just want to fix this before I leave and I don’t know if that’s possible. I’m spiraling and hoping this all just blows over.

(Sorry if this is all discombobulated, I just needed to get all of this out somewhere so i can sleep tonight.)

TL;DR - I asked if my boyfriend could come to family dinner and ruined the shred of mental health stability that I had.