Friend with a drinking/drug problem

Sorry for the long post…I have a friend/neighbor that has a drinking and possibly drug problem. We’ve been friends for a few years and our kids are around the same age and like to play together. She’s a single mom, but has 50/50 custody of her kiddo. Lately she’s been going through some life changes, and I know she’s been more stressed, but I think she’s starting to downward spiral. The last few times we hung out, it’s obvious she’s either drunk or stoned with and without her son around. She texts me often wanting to hang out, or she’ll ask me to drop off my kids at her house so they can all play together, but I always make an excuse. I also have an infant, and she asks frequently to hold him, but I’m terrified she’s going to drop him. There is no way I’d leave either of my kids with her – I feel like she can barely take care of her own son. She usually wants to go to our neighborhood pool together, and I think it’s because she wants to get drunk and let other people watch her kid. This weekend, my husband and I had some friends over, and she and some other neighbor friends met us at the pool. As soon as I saw her, she was already slurring her words. One of the other moms looked at me and said, “Wow, she’s wasted.” A couple of times when I’ve been out with her, I ended up babysitting all the kids AND her because she’s trashed. I’ve told her I’m worried about her, and that it’s dangerous to act that way around her son, especially since she’s a single mother. Several of our other neighborhood friends are starting to notice her behavior too and have made comments to me. I really do love and care about her, but it’s getting to the point I don’t want to be around her anymore. She’s constantly texting me to hang out, or she’ll ask me to invite her when I get together with my other mom friends. In a way I feel like she’s using me to find other friends or playdates for her son. I feel bad because I want her to get help, but it’s wearing me out and annoying me at the same time. What do I do??