Anxiety over work event due to BPD and health conditions

I have borderline personality disorder too so this ties into a scenario I don't want to be in. Tomorrow, my boyfriend and I are going to work at a Kayak and Canoe place. It's usually fun but I have a problem with someone who works there and frequents there and even though we NEED this money really really badly, I don't want to go. She will try to talk to me and I do not want anything to do with her. My partner also has BPD and wants to spend his time with me still on his weekends off from his normal job. I could throw up from the anxiety I have right now over it and I'm dreading it. I also don't do well in hot weather due to other health conditions too and we'd be there 9-5ish . I don't want to go, I don't want to go. I've let my boyfriend know I'm afraid to go but he didn't say anything to me about it. and I don't want to tell him again and he just say "eff it, we won't go" we NEED this money. I wish he was okay with me not going.