Let's say I always MO when i go to the bathroom, naturally if I am alone in the bathroom I am likely to be triggered due to past events. Can you overcome this by exposing yourself to the trigger without acting upon it? Will it fade away on its own? Or will the trigger stay for the rest of my life?
You encouraging the habit one or other way. You have to eliminate the thought itself, thereby the habit. Root cause is in your mind.
Exposure therapy has many functions but the one I find to be most important is decoupling a behavior from another. When we have a habit or worst case scenario, an addiction, we pair certain thought or actions with other specific thoughts or actions. In case of pmo addiction, we paired looking at images/porn with masturbation and arousal and we paired arousal with masturbation rather than sex. By exposure therapy, basically by looking but not touching yourself and by not getting aroused, you decouple arousal from watching images and you decouple arousal from masturbation. This teaches you first that you can get aroused but you don't HAVE to masturbate (it's actually normal to get aroused sometimes but not do anything) and in later stages teaches you you should not get aroused by watching pics in the first place (and the fact that you watched it for some time and DIDN'T masturbate will help you achieve this because your brain understands over time that simply watching pics will no longer result -further down the line- in a significant amount of pleasure - which masturbation and orgasm is). I mentioned the 2 weeks mark because in my former topic https://www.nofap.com/forum/index.php?threads/chart-of-the-streaks-of-over-9k-people.210744/ and from personal experience the first 2 weeks are by far the hardest and you're extremely likely to relapse if you do exposure that early. Your brain is more or less on autopilot in those two weeks and all your energy should go into not thinking about or watching any porn.