Very unique situation? How to tell someone I'm pregnant?

So i am in a very unique situation. I am 18 and i am pregnant. I am not married to my boyfriend or anything, but we are keeping the baby. This isn't necessarily a good thing that I'm pregnant, but its not a bad thing either. We are making the best of it. Soo my question is... i work for a lady as her babysitter mon-fri. We have became very close in the past about six months that i have been working for her. We have a lot of talks about life and my boyfriend and often she serves as a mother figure to me and she will tell me not to have babies young and to get out and live on my own to get experience and just things most mothers say. And just the other day something came up and she said to her daughter "no she's too young to have a baby!" referring to me. Now, I just have to tell her. And I cant figure out how to. I really dont think i am going to be able to make myself say it, it makes me feel sick just thinking about telling her. I really wish i could text her, but i know that would make me look stupid. and i dont want to write her a letter or anything like that. I just dont know how to tell her, but i have to because we are so close and i want to keep working for her for a long time. Please help if you have any suggestions or advice that would be great. Thanks!