Should I stop telling me gf?

I've been cutting for the last 2 years roughly, I got with my gf a little over a year ago now and we've both had rough pasts and connected over it, she told me I should tell her whenever I get thoughts or feel like cutting but whenever I do she gets sad and i hate to see her like that and I feel like a dissapointment to her. Should I keep telling her or should I just keep it to myself? I tried not telling her before but then she got mad when she saw the fresh cuts

Edit: we are both 16-19