Seems like your still in love with Karen. Without a doubt.
On the other hand, she might not have loved you the same since all she did was hear a rumor and broke it off. That should give you the incentive to let go of Karen and focus on Tina. If Tina is a great girl and you see yourself having the same relationship with her as you did with Karen, then go for it! What do you have to lose? Except the feeling of letting a former love go! And that great when you get that closure! Good luck!

If it's been 3 years since you've spoken to Karen then you NEED to give it up. Forget about Karen and try to make a new love. I doubt you guys are ever going to rekindle your love.
Move on sweetheart.