It’s obvious seeing him caused you to spiral, and now it seems you’re struggling with NC and guilt from following your attorney’s advice. This is why we keep suggesting not seeing him and no live interactions. It’s unnecessary. Many of us have separated households with ex’s with a minimum of contact. Email exists. You have an attorney. LH gave you a great sample text to send. The sooner you cut live contact again, the easier moving on becomes. He’s moved on.
It sounds like therapy would be incredibly helpful.