I've always been in love with a man who I met 7 years ago
does not gel with:
Around 4 years ago I moved to 'his' city for work but we missed each other as I was seeing someone and he was single
or:
He did ask me out once but at the time I was in a relationship
You were seeing someone else, remained seeing someone else, and refused to go out with the man you are apparently in love with?
I hope you're joking about contacting him to either congratulate him or tell him you love him. It's a fucking terrible idea, and an utterly selfish one.
Given that:
When I then became single, it transpired he was seeing someone
didn't cause him to run into your arms last time, then I really don't see why this time is any different.
He is going to ignore you. And you will have tried to deliberately sabotage what should be a lovely week for him and his soon-to-be-wife. Who, I'm sure, loves him as much as is humanly possible.
Get a grip