Husbands triggers cheating

How do you help someone who’s been cheated on numerous times in their past and get horribly triggered over the pettiest or things.. I try so hard to be patient but when he’s triggered it’s like the world is ending and he wants to run away..

Last night on Facebook my husbands friend that works out with him posted a gym pic of his legs and how huge they’ve grown. Over 100 people liked it and I was proud the dude finally got rid of his chicken legs.. my husband saw and flipped out. I’ve never done anything to him to make him feel this way.. I feel like I’m walking on egg shells.

Update:

The picture was of the guy belly button down with boxers on.. yeah it showed his abs.. was I wrong to like it even tho my intentions was just supporting him bettering himself??