Am I wrong for locking up my prescription painkillers from my girlfriend?

I have a few health conditions that can be quite painful. They require me to keep a fairly strict diet and exercise regime to give my body the best chances, but also, I have access to strong painkillers for bad days when I still need to function, and REALLY strong painkillers for REALLY bad days when I can afford to just relax.

I try to avoid taking them as much as I can because a) I don't want a tolerance and b) I don't want to get addicted.

I've noticed lately the last few times that it seems like there's less there than there should be. I thought maybe I'd taken them and not remembered, so I started just noting when I took them and how many, and sure enough, there's more missing.

I asked my girlfriend about it and she admitted to taking them when she had "REALLY bad period pain". I told her she is NOT to take my prescription pain killers, plus if I go through them too quickly they won't renew my script and I may not be able to get them when I need them, I told her I was really annoyed she didn't even ask, and basically it's illegal to take someone else's prescription medication.

She got a bit annoyed and making up excuses "you don't know as a man how bad this pain is" and "if you cared about me you'd care about my pain".

I told her to stop taking my medication, and she got fired up and said "don't tell me what I can and can't do".

So, I packed them in my briefcase, and that day bought a locking safe and put it in my closet.

It took about two weeks before she started making comments about me "hiding" my meds, like I "don't trust her". I said they aren't hidden, they're locked in my safe. She demanded the PIN, saying I shouldn't hide things from her, and I said that I don't trust her not to touch my meds, and she's not getting the PIN.

She brought some of her friends in on the argument, they're on her side, but I'm not budging. I said if she needs meds, see her GP. She said doctors don't understand and won't give her any. Am I really in the wrong here?

Am I wrong for locking up my prescription painkillers from my girlfriend?
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