I treat women badly in my sex life, am I feminist or sexist?

People don’t become feminists overnight.
I am in my late 20s and sex loving guy. Recently a girl in our group – a self-proclaimed feminist – said that I treat women badly I’m not a feminist. In referrence to fact that I have one night stands I sleep with multiple women and lie to them about it, and that I often lead women on, making them think I like them more than I like others.

I know these things are bad I lie to them, I know that I have held women to different standards than I hold myself – for example, I once shouted at my ex because she slept with someone we knew, even though I’d done the same – but honestly, I knew it was bad, I just couldn’t control my feelings. I have never myself to be sexist; I thought I was just selfishness, and I don’t think I treat women badly. To be honest, I was quite outraged by this new friend's comments, and initially I was very defensive. In my group of friends – who are your typical group of laddish guys who go to Ibiza – I’ve always been the one who takes feminism seriously while they dismiss it. I don’t think I objectify women, I think I treat them well. I always try to talk to women and men on the same level, I try to confront sexism in the office, and not to use sexually demeaning words about women. Women have never called me aggressive before her, she totally changed my thinking about myself. I don’t even tell sexist or porn jokes.

I’m confused and I am taking my friend’s comments seriously. Can I treat women badly in my sex life but still be a feminist? Is lying to women is sexism?