Wife is emotionally cheating, leaving me in limbo

My wife (36F) and I (38M) have been together for over 10 years. We got married last year. It has been a difficult year since, with ups and downs. I attempted a business venture that failed, and went into depression. I've been on the recovery and things were going well the past few months.

But recently, she started taking salsa lessons. I fully supported this and went to a few lessons but personally didn't enjoy it, so I simply gave her my blessing to continue. I fully trusted her. We have always been very open about the fact that being in a relationship requires a level of sacrifice, and have discussed crushes on people at work, and openly mention other people are attractive. I have always said I would be open to an open relationship if we discussed it - it seems like a practical solution for many couples, especially after a certain point, but of course with its risks. But as far as I know, neither of us have ever taken any action.

That is, until she started developing feelings for her salsa teacher. Instead of telling me, she decided to "explore the feeling". We went on a trip where she was very withdrawn, and she apologized and came clean afterward. That was about a month ago. I told her I had no problem with her continuing salsa, since it was clearly an enjoyable activity for her by itself. I asked her not to pursue this guy, and said we could discuss it openly, however she wanted. She agreed.

However, she continued pursuing lessons with this guy, including private lessons and finding him at salsa events in town. She started coming home later than usual from events. She denies doing anything, saying she is still unsure of what to do. She says she knows she is being selfish, and when I challenged her on her commitment to the relationship - which includes working through these things together, instead of closing the other out and doing things in secret - she said she wasn't committed any more, and needed to be selfish.

It's been 2-3 months now since this started, and I don't know what to do. I don't want to lose this relationship over something silly - I want to support her, and respect her, but I have to respect myself as well. I am too involved in the situation, so I am hoping for feedback from others who have been in a similar situation. Is my marriage already over? Do I have any say in this matter? Is it alright to be angry? I still love her completely and never changed my commitment, but this is painful.

We were trying for kids the past year as well, and weren't successful. There was a fair amount of stress, and my depression certainly played a role. That said, it's not exactly new... I'm the same, if not better than I have been over the years, which she agrees with.

TLDR: My loving supportive wife and partner of 10+ years got excited by an attractive salsa teacher and is panicking about the fact that she'll never get a chance to pursue this type of "spark", so she's apparently just going to pursue it regardless of the consequences, and finding this answer on her own is more important than our partnership.