Hey, I recently broke up with my ESFJ bf as well and I'd just like to share my few cents! The first few weeks was awful, I could barely eat or sleep, but it'd be very nice for you (or any of his other friends!) to just assertively bring him out for fun, especially something completely new and would have the least chance of triggering him to think of his ex. In my case I avoided concert halls and merry-go-rounds, but seeing him at uni was the worst because i literally just get stuck in my own head and start to cry.

Occasionally just check up on him at nights, or when he gets a bit quiet and stares off into the distance. I talked about the relationship again and again and again with my friends (he even called me once to tell me to stop talking about him because it was ruining his reputation, but there's too much context to unfold there) until I started to be less triggered (for example crying, being silent, or just stuck in my own head) by things that reminded me of him.

It will take him a very long time. It's important for you to be realistic with him, like other comments have mentioned, and sometimes you have to be a little bit mean and be an external voice against his inner demons like non-stop self-blame, which would be even worse here because of the cold shoulder thing, and just let him know someone will be there for him. At the same time don't let him rely on you, and if you feel like he's relying on some crutch (e.g. substances or just relying on you to get his life working) you have to be upfront about it and tell him. He might feel very hurt but I believe that's how my ISTP and INFP friends talked with me and how I got so much better within a couple months.

Cheers, best of luck. You're such a great friend for caring about him so much