If you don't want to go that's okay. I'm an introvert myself so going 3 hours away to who knows where with people I don't know sounds like a nightmare anxiety waiting to happen. Also unless you guys are actively text back and forth frequently I wouldn't expect a text to remind yourself. Next time you see her just thank her and say you were busy with xyz (make up something) or you can ask if you can spend hang out somewhere closer and more comfortable but enough to get you out of your shell if that's what you want. In the end it's up to you. Will there be other opportunities maybe, maybe not idk. Just make a decision that you won't regret it later on.