My (26m) gf (25f) has crippling social anxiety and it's getting worse. How can I save the relationship?

We have been together for 5 years. I didn't know what love was until I met her, and our relationship is almost perfect in every aspect besides one. She has the worst social anxiety of anybody I've ever met. She has a few friends and she is close with her family, but she is extremely withdrawn around strangers. I have seen her be driven to tears at the prospect of dealing with retail staff in a store. Ordinarily these issues would be something I could support her through, but the serious problem is her complete refusal to have any contact with my family. If we built a life together I would basically never see them, and my parents would barely even know their daughter in law or their grandkids. I hate feeling like I have to choose between my family and the love of my life. She refuses to see a therapist because she would be too frightened. We also have a nonrefundable, extremely expensive once in a life time trip booked later this year. Is there any way to salvage this situation or do I really just have to choose between her and my family?