@Charcoal_Wolf Sounds like you do really care about your friend, so might be something you bring to the table if you have this conversation with her. Can certainly be difficult having those kinds of conversations, but generally even if they're super awkward, they're worth it! Because at least then you'll know where you stand, ya know? Like you'll know if she's going to be willing to respect your boundaries. And might even give her an opportunity to be honest about what's going on for her and why she's started skipping.
If it's a tough conversation to have with your mum, you could always give Kids Helpline a buzz to talk it through with them, and maybe ask them if you could practice or get some tips on both of these tough conversations.