That is the best advice I can give ^^^^
Communication is important in any relationship; especially with guys like us.
I used to get mad at John for triggering me. I still sometimes fly off the handle but my freak outs have lessened in part because he's learning about triggers.
The other day he came up behind me and said "I'm behind you." Then he put his arms around me. If he had not warned me, I would have freaked out. I don't mind hugs but I need to see them coming and I can't see what's happening behind me.
So being able to communicate and having an understanding & patient companion is pretty important. Keep the lines of communication open. Let the other person know when something is bothering you, preferably when it's still happening. Why let the agony continue and possibly damage the relationship?
Just say, "being held is very triggering for me right now" or explain what is bothering you. It's not always clear to us why exactly we react in certain ways, but it's important to note that we are experiencing an unpleasant reaction and we would like it to stop.
I'm learning that our companions need to be just as dedicated as we are. We should be able to open up but they need to be able to understand, respect our boundaries, and not take our reactions to their intimate gestures personally.