bf messaging another woman saying he loves her

So today I found the proof that my bf has been up to no good 😔
I've had my suspicions for a few months now and we've had countless arguments over things. Today he left his fb open and in the messages was messages between him and this other woman. He said he loves her, call her princess and sexy. All the things he's calls me!! We were meant to be getting married and we've been ttc for almost 3 yrs now. There were also naked pictures exchanged between them!
I took screenshots so he couldn't of denied it I'm absolutely heartbroken over this. I know it's gone no further than messaging as we live 130 miles away from this girls and we don't have a car.Â