To answer your title question... well, I get stuck in loops. When I'm in a stressful situation I get trapped. Constant research and reaching to escape the loop but it just keeps me in the loop. Yes, it's very obsessive. Loops can last a few hour to months, depending on the situation.

As for the guy.... I think maybe you need to move on from him. He doesn't sound healthy. Friends with benefits is not a good idea. Someone who already betrays by going back to his ex all the time, not a good idea. This person has his own issues and it isn't healthy for you to be stuck on him. I know it's hard, but you have to break away. He's playing with your heart and you deserve better than that!

Also, you need to get away from the other woman, too. You just need to get away.

Step 1: delete their contact information and block them. Don't allow any contact. If you have them on social sites, block them. Remove them as friends. Block their calls, delete their numbers, don't text.

Step 2: you need to learn coping skills. Do you have a therapist? If not, maybe a good idea is to get one. You need someone to help you navigate out of this.

Step 3: start finding things that you like to do that nurture you. This is going to be tough. At first your mind will wander and you'll be distracted a lot. But don't give up. Keep working at it.

Anyway, those are my tips. I hope they help. but getting away from the toxic people will be a huge help to you!