I can't ask for the money I lent my girlfriend back, it's so embarrassing.

When I was with my ex, I took a cash advance from my credit card to help him out with some trouble he was having. Now we’ve broken up, but I haven’t heard a peep from him, so he’s pretty much just sat on my money. My situation isn’t great either; I’m paying the installments every month, but honestly, I’m quite hesitant to write to him. Do you think I should chase after that money or just drink a cold water and let it go? I'm really feeling down.