I have -0.50 in one eye and the other one is perfect. should i wear glasses? if so, is it possible to wear contacts instead of glasses.

You may only need: one contact, if that. If you can see relatively well, you don't need to wear glasses. For perfect vision, your one eye would need a lens. However, many people are perfectly happy with 20/25 or 20/30 or 20/40 vision in one eye. So, you can wear glasses with a plano (clear) glass for your 20/20 eye if you want. Know that with contacts, you need to take good care of your eye and not overwear them.