Terribly sorry about your personal experience, truly.
But with all due respect, this is also the first time for me to hear about the word being classified as a slur.
Trap is like what the other person mentioned, it is meant to classify someone that acts/dresses to be like the other gender in general I.e. a male that dresses up like a female. Typically those that goes out of their way to do so.
As for femboys, those are typically the ones that usually have a more naturally feminine physique and stature if I can recall it right. I played games with them a a focus a number of times now and yeah. Regardless if they actually have the intention of being feminine or not.
Though not an expert on it, just info from the top of my head.
To my knowledge, the community at large does not use it as a slur or to be transphobic. I think in your case, it was just used like that and gave you that impression.
On that note, not sure if author updated the game to accomodate your concern but I don't think they need to change anything about it.
If you do a quick search, trap is an actual tag that is used regularly within relevant circles. And there are people that indeed like them.
As for you being a Trans, I think that's in its own category I reckon. Different from traps.