I'm mad at my gf for smoking some cigs
Why are you angry at her for smoking?
Because I started to cough a lot
I can see why this would make you upset. It's understandable to be upset at a partner who is damaging their health. You should politely ask them not to smoke while you are around.
I think that's a great idea. Thank you.
I'm sure once she knows that you don't feel well when she smokes around you then she'll stop because she cares about your wellbeing.