Just stay as calm as you can be. Say something like "I have feelings for you" or maybe "so do you have feelings for me?" Or maybe "you'll date anyone that asks a question?" Just try and stay calm is the key. Being yourself is another main thing.

That's at least how my relationships have been successful. I've been myself and just came out with my feelings. Social anxiety sucks big time, so I can understand being calm might be tricky, so maybe try meditating a bit before you message them.