Return it. Right now, it's your jacket, but only as a decoration to your wardrobe. Are you actively loosing weight now? are you enrolled or in the middle of a diet/lifestyle change/WW/etc? If not, that jacket is not the motivation you need. Most people feel they "need " to lose some pounds, but are generally ok with them so don't make and generally don't need to make the effort right now. You should buy something that you love on yourself, that makes you love you RIGHT NOW. I say it's ok to keep some things you actually wore , in the hopes you might wear them again, but don't waste money and emotions on things that you can't wear now. It's not good for your wallet/self-esteem. You are perfect right now, do you want to start dieting because of a bargain sale?
That being said, that jacket can make an awesome gift. I remember i received a leather jacket that exact colour when i was 16, from a neighbor. I couldn't have afforded such thing, and it was a very kind gesture.