Is the money I took from my relative unlawful? Is selling stocks in which I lost money permissible in order to repay debts? And with which of the debts should I begin repayment, knowing that the amount only covers one of the two loans?

Whatever the creditor refused to accept from the loan is yours, and your disposal of it is permissible. What he lent you remains your obligation until you repay it. One must beware of procrastinating in repaying debts, for the Prophet (peace be upon him) said: "The soul of the believer is suspended by his debt until it is paid off," and "Every sin of the martyr is forgiven except debt."

It is also obligatory to repent from dealing with interest-based credit cards, for Allah the Almighty says: "O you who have believed, fear Allah and give up what remains [due to you] of interest, if you should be believers. And if you do not, then be informed of a war from Allah and His Messenger," and the Prophet (peace be upon him) said: "The Messenger of Allah (peace be upon him) cursed the one who consumes Riba (interest), its payer, its scribe, and its two witnesses, and he said: 'They are all equal (in sin).'"

If the proceeds from selling your shares are not sufficient to repay all your current debts, then the loan from the man and the credit card loan must be apportioned, unless one of the two debts is deferred and the other is immediate, in which case the immediate one is paid first. Or, if delaying the payment of the credit card loan results in an increase in interest, then it must be paid first to get rid of the forbidden interest. It is recommended to seek permission from the other creditor for the delay.