All signs point to run and kudos for having a good lawyer to tell you to not pay any of his debts
How long have you two been dating?
Also, a gentle way to tell him no would be that you jeopardizing a huge portion of your trust isn’t what would what you to do.
Let me be absolutely clear here:
> How can I express this to him without ending my relationship?
Ending your relationship with him should be at the top of your list, not something you should be trying to avoid.
Right now, he’s in debt. Which is his problem. And he wants you to annihilate your savings, sell your house, so that you can solve his problem for him. And (not so incidentally) turn it into your problem.
Because when (not if, when) he fails to pay you back, and then breaks up with you because “You’re just being so pushy about money and I just can’t take it any more”, he will be debt-free, and you will have lost your savings.
Say “no”. Don’t explain, don’t bend.
If you not wanting to crater your savings in order to get him out of a mess he created for himself is enough to make him want to leave you, then you are better off without him.
Personally, if it were me, I could consider the fact that he asked something that outrageous to be reason enough to be reconsidering being in a relationship with him, because it speaks to his willingness to take huge advantage of you.
Oh, and this:
>He wants me to pay all of his debt down and then repay it back to me so that he doesn’t have to pay interest.
…means that he wants you to give him free money, because by saving him interest, you would be costing yourself the interest or appreciation your money would be earning if it stayed where it is.
He’s using you, flat-out, no question.