OK, let us assume he now gets his arse in gear and applies for the visa within the deadline.
Lets look at where does that leave you:
He borrowed from you DM before and has no intention of repaying her.
You and he have other debts - in whose name are these? Are they actually your debts or his?
And now he is borrowing from a friend - do you honestly think he will repay his friend, or will he just lose the friendship and trash his good name in that circle of people who know him?
Can you see that he is dragging you down. You need to make plans to extricate yourself from this financial mess.
Do you have your own current account as well as a joint account?
Do you keep track of what each of you contribute to the household and children, and what each of you has for 'personal' money? (The easiest way to do this is to have a joint account for house and children, into which you both pay an agreed amount, and each have personal current accounts for 'pocket money').
What are the plans for paying off the existing debts? Who is paying them? Were they for household and childcare costs, or personal debts?
Did he let you run up debts for essential household costs because he was not paying into the joint account enough from his wages?
As a married couple, your finances are legally linked, but you can still set some boundaries around his behaviour by using joint and personal accounts and insisting on a fair system for managing your finances.