Welcome to PC Eckman Spiral
Sorry to hear about your girlfriend's business not working out.

I have, unfortunately, worked for very small businesses before. They are
real tough to get going ~ even in a decent economy! With the poor economy, they are even more challenging.
It is too bad that your gf wasn't real honest and upfront about what was happening. :sad: Thankfully, there is a light at the end of the tunnel for you. A chapter to add to your book of experiences. I would assume that there were some good times in those nine years too. Try not to block entire memory of the relationship, that just seems sad to me.
Hopefully, your ex has learned from the experience ~ as you have. I would imagine that you will be more careful on lending money in the future.
Lending money between friends and/or family
almost always leads to disappointment and resentment. Very sad to see.

Personally, I'd recommend not "lending". If you can't afford (or don't want) to give the money away, don't do it. If you're fine with giving it away to "Joe", go ahead & hopefully he will re-pay you and it will be a fabulous surprise!
Very best wishes to you ~ take care!