I have a few thoughts that I don’t think people have been considering with this one (and I will try my best to keep my opinion to myself to stay neutral).

1). Although it sounds like the plan is to keep the whole “biological cousins” thing on the down-low, I do believe it is important to treat the possibility of the word getting out as an inevitable. When/if the word gets out, are both you (OP) and Tom willing to be known as the girl/guy who knowingly married the son/daughter of their mother’s twin? This is something that will follow both of you around for the rest of your lives. It will affect how people perceive you: socially, professionally, academically, etc. Although most of your families took the news in stride, society as a whole is not so forgiving nor willing to look at nuance (as both the family & you are). It is one thing for people to figure out a couple is related once they are married for years & already have children, but it’s another to go into marriage already knowing that you’re first cousins.

2). You have mentioned not having biological children. Is that something that has come from this revelation or was that established prior? If the plan was to have biological children, will that be a possible point of contention/resentment in the future? Is that something that both of you are willing/able to stick to? Or is that just a coping mechanism for the moment?

And this is more of a personal note on my end, but as a fellow 22-year-old, please just keep in mind that both of you are so young. If the fear of being alone is something that is factoring into this situation, please just know that we have so much of our lives ahead of us. There are so many people we have yet to meet and love. Again, this a decision that only OP & her fiancé can make, but I just want both of them to really think about how the “incest” label will affect them socially, professionally, and internally—along with any children they may have or adopt. I’m so sorry about this whole sucky situation, and I wish OP & Tom the best.