It depends how you forward you want to be. You could say I'm finding it hard to interact with you as I feel like you're pushing your opinions on me - forward. Politely decline any favours that are asked of you - less forward. You're not horrible. You can't get along with everyone.
Realistically, how much more interaction will you be having with her in the future? You said she attends some of the same classes as you - If you’re due any day now how many more classes will you cross paths in? Soon you’ll be in the thick of adapting to newborn life and she’ll likely just get lost in the shuffle. It could be the perfect opportunity for a natural separation. I’d really only address it if you plan on staying friends with her, which it sounds like isn’t the case based on how you ended your post.
You can either take the bold route where either you or your husband speak up next time she’s being too opinionated, or you can just refuse the favours she’s asking for by saying “I’m sorry, that’s not something I can help you with” and hope she gets the huff and finds someone else to badger!
“I really need to get into the proper headspace for birth. I appreciate your advice since you’ve done this before, but I’m here to learn about what will work for me since ✨as you know✨every birth is different.” Hope that helps. If not, maybe you can talk to the midwife so she can address it seems like she’s affecting others too.
You’re not a horrible person at all, I completely understand … I would just be honest with her, just say everyone is entitled to their opinion but you don’t share the same opinions as her and you’d appreciate if she didn’t shove them down you’re throat then if she still insists just say you feel you can’t be friends if she can’t respect you’re wishes ! That’s what I would do but I’m quite a “Say it how it is person with no filter” I hope this helps …