How can I do it? I have a girl that I fucked, she wants a relationship. I don't mind, but I also don't want to be exclusive with her.

What do I do?

I've been in that situation a lot of times. So here it goes;

Lets call the girl u fucked "Lisa" just to have a name.
Meet Lisa in Real life, not over Live messenger or SMS or something like that. Meet her and tell her that you don't want to commit into a relationship yet. Because ur' not ready to be in a relationship. Tell her that u love spending time with her, and u like her really good. But you don't want to rush things. And then she won't say anything for some seconds because she's kinda "muted". It's almost guaranteed that she will agree with you, that she won't rush either. But if she gets angry etc. Then just say; "It's not that I don't like you, trust me I do. But I really hope that u can understand that I need a little time to get used to this." And if she don't agrees then, then u can just "throw her away". Since then she's not listening to what u gotta say, and ur feelings'.

But if it works:
Then ur still free as the bird my friend. U can still make out and flirt with other people, and still not be cheating, since ur' not really committed to the girl. But if u really like the girl, then i advise you to not flirt and make out with other girls, since u'll feel sorry for her, bigtime. (Been there, done that.) But it's up to you now. Now you know what to do. Go do it in real life

Hope it helps.

Regards,
Hummle91