I am going thru something like that right now. And the outcome was that my mother found out from someone else on my biological dad's side of the family and is holding it more over my head. My mother and I do not get along at all and never have since I was a little girl. She is currently trying to get custody of my 2 yr old son because she does not like my fiance (when she never met him or seen him) but CLAIMS its because I am an unfit mother and he's being mistreated which is SO not true. And now she is badmouthing me to everyone she knows and to everyone that will listen. Its stressing me out very much with my current pregnancy and I cant stand it plus I want her to leave us alone and give me my son back and let us live our lives happily. If you feel your mom will make your life a living hell more so than now, then I say dont tell her but also be ready to face if she finds out about it from someone else. Its the ppl you think would never tell your business that do tell it. Or if you just wanna tell her out of courtesy and to avoid someone else telling her then I say tell her. But either way, try not to stress about what may or may not happen. Its easier said than done but stress is not good for you or your unborn child. Trust me, I have cried many of days at the hateful stuff my mom is saying and doing to me and STILL is doing to me but all you can do is stay strong and fight thru it. Never give up and dont fight for what you believe in. Just make sure that your husband is there for you no matter what because it is very hard when you do not have a support system of some type. If you wanna talk more, you can always PM me or somethin. Hope things work out for you.