Brother won't let me see my niece anymore

When my niece June was a few months old my brother brother's girlfriend died and he became an alcoholic. It was so bad that he ended up losing custody of her and me and my husband took guardianship. Neither me or my husband can have kids and we got June when she was 6 months old. We took care of her while my brother went to rehab and therapy. He had some issues with relapse and we honestly thought court would terminate his rights and we planned to adopt June but he was granted custody again when she was 2. He's stayed sober as far as I know but after having June for almost 2 years she basically became our daughter. We had her since she was a baby. I have gotten really paranoid about June and wondering if she's okay and if my brother is actually staying sober. I've called CPS a few times just so they could hopefully randomly pop up to make sure my brother is doing what he needs to be doing. June is 5 now and my brother has stayed sober but my anxiety for June won't let me completely trust him with her. June was sick and my brother needed to go to work so me and my husband agreed to watch her. He left her medicine and Pedialyte. Idk why. It's probably my anxiety because I'm always anxious and thinking the worst when it comes to that little girl. I love her! I just started worrying that my brother put drugs on her stuff. He had never done that before. Idk why I was so paranoid but I through our jer Pedialyte and medicine. When my brother came back and found out he was pissed and said he may have had a drinking problem before but he never touched drugs or gave June drugs and I had no reason to think that. Now he has to go try to get a prescription for her medicine again. I said I was just looking out for June and I'm sorry but he's saying I need a break from June and he doesn't want me around his daughter for a while. I already apologized and now I can't see her. I know what I did was wrong but all I've done since that little girl was a baby is look out for her.