being upset about the sex

We aren't finding out the sex of our baby. We would like a suprise. But I can't help but hate it if I was to have a boy. I'm crying daily at the thought of it and I've convinced myself it's a boy and some days I feel as if I could just get rid of it :(. I never would but I'm just getting more and more upset about it. I'd love a girl. My partner has a boy and we would love a girl because of that. Even though I said from the start I wouldn't mind what we have as long as it's healthy. But I now feel guilty about how I feel. How do I stop this?!!