I suppose if it's meant to be, it will be. But PLEASE don't do anything to ruin his marriage. If you do, your relationship WILL be doomed.
You may have to wait years -- but if it's to be, it will be. If it's not, it won't.
I'm not sure I'd waste my life on that ~ you only are given ONE life to live. Do you want to spend it alone? I'd think about that. You may just end up all alone if you wait for him.
God bless and please take care. Hugs, Lee