People occupy job titles In our lives (mother, brother, friend, spouse, doctor etc) where the assumption is they will be there for you when you need them. And so when they betray you it can be hard to take.
The Impulse is to get very angry because surely they will see how hurt you are and change their behavior. But sometimes the way they treat you is not an accident. And at that point you have to wish them well but distance yourself from them. You have to move on for your emotional health