Pregnancy

I had sex with my ex a few weeks ago and since then we haven't been on good terms. At the moment we don't talk and we have a lot of hatred towards each other. My period is a week late and I think I may be pregnant. If I find out I am pregnant how do I tell him or do I not tell him at all. We haven't spoken and last time we did it ended bad and we decided not to be in each others life.