Why am I doing this to myself?!?

For over a year I've been seeing a closeted farmer guy younger than myself. We've been together every day since we met and practically live with each other. I caught him cheating on me back in January but because he is younger and inexperienced with relationships, (I went through a slut phase too) I forgave him. I've caught him with online profiles twice and we deleted them together. Recently he left his email signed in on my computer and he has been talking to one of his old "hook-ups". He won't tell any of his family or friends about me because they're conservative and he's expected to eventually take over the family farm.

This is the first serious relationship I've been in and I'm having a difficult time ending it. We can say to each other that we're in love but love isn't supposed to hurt like this. I feel like if I end the relationship my life will be over. I've been completely faithful and his betrayal is tearing me apart. I'm finding it hard to focus on anything else; to the point that I don't even have an appetite. We live in a very rural area and the idea of being alone again is driving me insane.

I need some advice on how to let go and move on with my life productively.

Thanks.