How to talk to Christian in laws about messianics

I’m honestly so confused by this entire situation and need help navigating it. For background, I’m not halakhically Jewish, I still need to officially convert. My fiancé is Christian, but not really practicing. His family are very active in the church (Baptist mega churches). His mom works at the church and oversees the events/classes they have.

His mother invited me to an event that her church is hosting to learn about “the seven annual and one weekly Jewish festivals” (red flag). It is being held on Shabbat (and yes they are charging for people to go). I asked if one of the Rabbis from the nearby synagogue was going to be speaking and was informed that it’s being hosted by Dr. (I’m not going to say) and his wife who are the leaders of the messianic “judaism” congregation. I don’t have much of a filter so my immediate response was “he’s not a rabbi. The messianic movement is just churches pretending to be synagogues to trick Jews into converting”. I did go on a little bit of a rant.

I looked the guy up when she left and he is a born and raised Christian and has only gone to Christian seminaries. He does have a Jewish last name and is leaning into that (which I think is gross).

I really don’t know how to handle it. I could just put Tovia Singer on the next time we’re in the car together but I don’t think that’ll go well in the long run. I could probably just ignore it, but (my understanding of her job is) she’s in charge of what events get the ok and I want to help her understand that this isn’t what tens of thousands of people should be learning thinking that it’s judaism. I also really don’t want her to get her hopes up about me converting to Christianity. I love his family, they’re really nice people, I just don’t know how to deal with them being misinformed. I don’t think this is a common scenario, but if anyone has gone through anything similar or has any ideas, I’m all ears.