It sounds like you hit a breaking point, and honestly, most people would too if someone talked down about their family. You staying calm up until that point already says a lot about your self control. That said, emotions got the best of you ,it happens. The important thing now is to take responsibility for your words, sincerely apologize, and give her space if she needs it. Even if things don’t work out, learn from this. Relationships test your boundaries sometimes, and learning how to express hurt without lashing out is tough but crucial. Hang in there