My bf's ex's engagement trigged his panic attack

We’ve been together for two years and just moved in. Everything felt stable and good… until last night. We were scrolling and his ex’s engagement post popped up. Their breakup was ugly — she cheated on him with the guy she’s now marrying — so I knew it was a sensitive topic, but I didn’t expect his reaction. He froze, shut down, and then in the middle of the night, he left. Phone off. No explanation. I thought something was seriously wrong. When he came back at 6 AM, he told me he had a panic attack. Not because he still loves her — but because seeing her “happy” triggered this fear that he’d never be able to feel that same pure happiness again, even with me. We talked for hours, cried, and he apologized. I told him disappearing like that can’t ever happen again. We’re considering therapy.

Would you forgive him in this situation? #AskLemon8 #letscaht