Fun Place With Sad Memories

My 18 year old sister is planning on taking my sister and I to a place for mini golf and other fun stuff today. I know it's supposed to be fun but I'm having a hard time wanting to go. You see, I went there once with my friend who just threw me away and I don't want to be faced with those memories. I literally just had a dream with her in it last night. I keep having dreams where she's wanting to be my friend and I'm surprised she wants to after what she did.

All I want to do is stay home and write my fan fiction I'm working on. But then I don't want to be judged by the other people there my sister is going with. One of which is a boy she really likes so I know she'll spend more time with him than me. I don't like being selfish, I just know I would need the support if I went.

I don't know what to do.