Gently, You need to stop giving a shit. I for one would laugh my arse off if he is being scammed.
He is no longer your problem. You are no longer his caretaker. Scammer or not he has made choices and the consequences of those choices are his. Don't forget you are also facing consequences from his choices - focus on dealing with those, not his self-inflicted problems.
If you are concerned about joint assets the talk to your L to protect your interests. Like yesterday.
Detachment will come but you need to work at it. Strict No Contact (NC) is key.
He is no longer your husband, your lover, your best friend. He no longer has your back. He is not your problem.
Repeat until it sticks.
((Gajit)) easier said than done - I know it. Please don't let your hopes stop you from protecting yourself. If you're talking to him while he's still with any other and unremorseful you are not protecting yourself, you are hurting yourself. Further, you are allowing him to cake eat - they'd cake eat forever if we let them.