I'm 39 and flying for the first time with fiancee and her family

EDIT-I don't have anxiety about flying or the safety of it. It's more about being embarrassed because my fiancee's family has much more travel experience than me and I don't want to make a fool of myself in front of them or look like a pleb/moron. I already have Real ID and have had it since 2018.

2ND EDIT-My fiancee's family know that I come from a family that had financial struggles and they know certain details such as family being on food stamps at one point, me having thrift store clothes. they know about my mom having struggles trying to get SSDI. But they are certain things they don't know such as me being homeless at one point as an adult after a job loss. I don't want them to know everything about my past struggles and my family's past struggles.

I have never flown before. My fiancee invited me on a trip with her and her family for a family reunion in July.

I'm pretty much a moron when it comes to traveling as I grew up in a family that had money struggles (dad was a police officer in a smaller city that didn't pay well and mom was diagonsed with multiple sclerosis and could only work part time and there were financial issues caused by her MS).

I asked my fiancee not to say anything about my lack of travel experience to her parents and two brothers who are traveling with us.

I want insight/advice from experienced travelers and I don't want to ask my girlfriend because she has already agreed to not say anything to her family about me having zero travel experience.

Please be kind, it's already embarrassing for me to have never traveled via plane.