Would it be wrong if i just kissed my ex boyfriend without saying anything?

Yes because you aren't being truthful with yourself or you wouldn't want to kiss him. You still have feelings for him. If you didn't a hug or a hello would be sufficient. 'Ex' means you are no longer going with that person so leave it lay. If you are still interested in him then get together and communicate your feelings properly (without sounding desperate) and see where it takes you.