Bachata sensual and relationships

Hello, everyone. Posting here with what’s probably an unusual question.

So this is the situation. My gf loves dancing, she says it is the only time she truly feels alive. She’s been taking bachata sensual classes for a couple of years now. I also started doing it, about 1.5 months ago so needless to say, I still have a lot to learn.

We go to different classes, because of work schedules. The school she takes classes in is by far the best in my country and she is adamant on continuing there so that she can maximize her potential.

My issue is that her ex is attending the same classes, which means they’d be practicing together. I am very uncomfortable with this, I feel that it is a sensual dance and I can’t stomach the idea of him touching her abdomen, bending her over, basically them doing a sensual activity together, especially since the songs are often about sex and seduction.

Their relationship finished on bad terms and they don’t dance with each other in the latino clubs or at festivals, only when switching partners during the courses, because she has to, as she puts it. She doesn’t want to refuse practicing with him there and skip to the next partner, cuz “it would be awkward” (quote). She also doesn’t want to go to a different school, due to the huge gap in skill level of the instructors (this is true, I investigated).

How do I navigate this situation? Is there a real reason for me to feel jealous? What is the take of people that have been dancing bachata sensual for quite some time? Is it truly inappropriate for him to be “touching” her, like I feel? Part of the reason I started taking classes is to better understand her viewpoint, but I need more time for that. For example, I think I will feel awkward when I will have to lead another girl into a body wave from behind, “conjoined” at the hips, touching her abdomen and holding hands while doing it. It seems a bit too intimate to me and it even looks a bit sexual.

Constructive criticism please, I am trying to understand and come to terms with the situation.