J,
Wow, I feel your stress emanating right through my screen.
Obsession is a toughie to deal with and my experience is minimal.. From both sides though, I sympathize with you and your friends. Obsession is hard, but dealing with a friend who has an obsession is just as difficult. Still, they are your friends, they should carry on supporting you whatever.

What you really need is a bit of tough love.
I mean. It's an obsession. You don't love him. You might not even know him very well. It's runaway infatuation. Are you projecting your fantasy of a perfect man onto Eric? Do you truly like him? Really?
You need to get tough with yourself, yet be fair with this situation.

It is inevitable that you will see this man, right? Firstly, accept it. All the stressing and panicking in the world won't help. You WILL see him. No negativity can change it.

You need to decide if you truly want this obsession to be over. How many hours of your life have you wasted thinking about him? It could be more than you think.
How many conversations have you monopolized discussing him? Probably a lot.
How much of your friend's lives have you been keeping track of while obsessing? Maybe not so much.
How does this affect your work performance and are you willing to be okay with that?
Obsessions dominate, and we don't realize how much until the damage has been done.

There is no fast and easy way out of this. But you do need to grab control of yourself, shake your shoulders hard and make priorities. What comes first, and thus, what gets your attention?

You then need to devalue your object of obsession. Eric is one man, one man of how many on this entire planet?
He is probably by no means the greatest of them, or even good for you. he probably has qualities that make you recoil.
What are these? How do these qualities alone make you feel? Forget who they are attached to. Look at the behaviour, look at what he does that is unpleasant. Every time a positive, dwelling, longing thought comes along, choose an equally strong unpleasant one regarding this man.

The scales seem to be tipped too far in his favour. You have the rational power to reduce this obsession.