Welcome to the forum. Good thing to come over here and get some advice.
I know how you feel. You gambled away someone else’s money. Then borrowed from 2 friends and lost that amount as well. That must feel very depressing and not knowing what to do. You’re still in the modus of gambling thrill, as I would like to call it.
So the most logical way out seems to get money as soon as possible. You need 300 dollars, that’s not an easy amount to get fast. When you have smaller amounts in reach, the most obvious thing to do is gamble again, hoping to win it all back. That saves you from not having to confess or make up excuses. Please don’t do that. The odds are against you and your friends most-likely have to wait longer to get their money back.
It’s a hard thing to do, but the easiest way out is to confess and tell them truly what happened. There are no excuses. If you don’t like to tell your friends, then you need to tell your parents or brother. Maybe they can help you out.
In the meanwhile earn the money back, seek help, visit a doctor and pay them of whenever you can.
Wish you the best, good luck!
Dave