I'm so sorry that you probably haven't got the response you were hoping for but I do think everybody on this thread is correct. If he loved you that much, he would be with you. There's obviously a reason he's not left his girlfriend (whether he says it's the mortgage and dog is irrelevant - if he wanted you that much he would be with you).
To love somebody so much and that feeling not be reciprocated in the same way is heartbreaking, I know, but it will subside. You will find somebody who is able to recognise your worth and want you, and only you. He's got you exactly where he wants you, he knows at the drop of a hat you will be there. It's easy to send somebody a text saying you love them, will do anything for them etc, but to actually show those feelings through your actions is another thing. Actions speak louder than words, and in this case, I think his words are nothing more than just words.
I really hope you're able to move on and find somebody who treats you and loves you exactly as you deserve. 12 years to leave you hanging is awful. Don't waste any more of your precious time.