One thing in coaching we quickly learn is that whenever you are triggered by someone else, it says something about you. If someone is wearing something, or saying something, or doing something, and that raises your heart rate, it is something inside you that is getting triggered. Coaches will work with the person to distinguish what this is and after this awareness comes, life usually changes for the better. It is one big reason why coaching is so effective.
All that being said, everyone can still be triggered. It is so easy to say to yourself "well now I know that I’m getting triggered because of something in my childhood so it won’t bother me anymore." When saying that we likely believe it to be true. However, it still takes practice. Do not be hard on yourself just because you slip back. Breaking habits takes a lot of repetition.
Not getting triggered takes practice. Remember that before you are hard on yourself. It will happen in time, just not quite this instant.