Has anyone got any tips for controlling their emotions?

I'm absolutely in love with a girl, and she doesn't know it. I'm planning on making a move soon.

I'm pretty good at playing it cool with her outwardly but inside, I actually don't feel like good.

When I think of her, it feels like someone punched me in the stomach. I look at her texts, especially when she hasn't replied in a while, and I almost feel sad. I've lost interest in talking to other girls. For some reason, I thought I'd be full of energy and happy with the potential of this but I'm actually lethargic and have no interest in eating, doing my usual activities etc. Everything feels a bit boring.

I'm just looking forward to something we have planned next week, but I'm also a bit nervous she'll cancel. She obviously doesn't know what I'm planning so it's not a big deal to her and it's a casual meeting so there's a chance she'll cancel so I'm nervous about that.

Obviously, I feel a bit lovesick. Far too preoccupied and it's affecting everything about me. I don't blame her, it's obviously me doing it to myself.

I don't like feeling like this. It's not cool, or helpful and I know it'll result in me saying or doing something silly eventually. It's too intense.

I would love to put her out of my mind and do other things and be all calm and controlled. But how do I stop emotions from kicking my ass? It's not something I'm doing deliberately.

Any tips?