Go and have fun.
A few more thoughts though.
- It sounds like you felt a bit out-of-place the first time, since you don't know much about classical music? I actually LOVE situations like these! They're super-easy to deal with. I tend to just say something along the lines of, "wow - that sounds so interesting! I've never really had a chance to learn much about classical music - tell me more!"
and people, who presumably enjoy this hobby/career, are generally happy to oblige. It gives you a way to interact with people and gives them a chance to talk about what they love.
- About her acting cheery when she saw you again... even if she DID intentionally snub you (which may not be the case) - what could she do? This is an awkward situation... she can't really frown and say, "oh gosh, I was hoping you weren't going to be here"
I think the polite thing to do is to act pseudo-friendly.
Just some random thoughts, hope you have a good time this year if you decide to go!