My ex's life is spiralling out of control and it's all because I dumped her. Was I right to react this way?

Anonymous
My ex-girlfriend comes from a well-off family and, as such, has never needed to work. We've been together for four years and just recently broke up. Here's the reason why:

My girlfriend's family always goes on summer vacations which, in the past, I've always been invited to go on. This time, however, I could not go with them to the Bahamas (this year's vacation destination) due to my financial situation and recently starting a new job that prevented me from taking time off. While away, she had a fling with a local and got pregnant with his child. When she returned and I found out about it, I kicked her to the curb because I could no longer trust her. She tried to defend herself by saying this would never have happened if I was there with her on vacation.

Her mother pretty much hates me for what I've done now, but her father thinks I'm in the right and is actually siding with me in this matter. And he's cutting off her access to the family money for her infidelity. He'll still give her an "allowance" due to the fact that she has a baby to support, but she won't be able to afford anything more than the bare necessities without getting a job.

Her mother is upset with her father's decision to cut her off financially and is threatening to divorce him unless he goes back on his decision, but he is adamant and unwavering.

What is your analysis of the situation? Was I right to dump her? We have no children and no shared financial resources so there's nothing concrete tying us together.
Updates
+1 y
I just want to iterate that when I dumped her for what she did, I had no idea it would have such a big impact on her family and home life. But the fact that her father stands by my decision makes me think I was most likely in the right.
My ex's life is spiralling out of control and it's all because I dumped her. Was I right to react this way?
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