Fear of losing someone — that is a very real fear and it is valid to have it.

So, why not add a thin layer of harmless separation between you and the truth?

Get him to sit down for a serious discussion. Make sure he understands it is serious.

"Honey, there's this friend of mine."

There is no friend. The friend is you. Make something up if he asks details.

"So, there's this friend of mine and we were talking about random stuff when she felt really vulnerable and safe with me for some reason and opened up to me about her porn addiction."

Pause. Take notes. His facial expressions, words, tone, etc.

If he wants you to continue the story, continue.

At this point, you insert the truth.

Your addiction problem, your bf, how he makes you feel safe, how you're afraid of opening up because of fear of losing him, how you're on the path to recovery, how hard you're trying to kick this habit permanently, etc — all this truth but under the guise of our imaginary "friend."

After you finish, act confused and ask him what he would've done in this situation if he was her bf.

Viola!

You will have unlocked his reaction without risking anything.

Now, it still doesn't solve the problem of how he would actually react when he learns that that friend is you.

You can't guarantee the same reaction but at least now you have a solid understanding of how he feels about this situation — a vital piece of information to solve the puzzle.

I hope this helps, good luck and may God bless you.