Overbearing Mother-in-Law! Help!

Thelma
It hasn't been a week since I learned that I'm pregnant w/ my 1st baby! I should say our 1st baby ... 
So much is happening in my mind... One of the first people we first told were our mom's. My family is more reserved and his family is totally the opposite. His mother wants to tell the world! She's so excited- I feel more for her own self than anything... When we told her I was pregnant she screamed and laughed... Said "I'm going to have a baby..." I couldn't understand why she would say that! She told her "you guys now def need to move in!" I was like.. "Hell no!" We asked for her not to share the news w anyone besides her husband and daughter which we told that same night... Later, turns out we also needed to inform her best friend and his partner... Fine! I reluctantly agreed! We agreed to tell her best friend the evening of his bday party. We asked that we keep it between ourselves and not to share w the rest of the guests. What happends! One of the guest comes in and she's 4 months pregnant w her first baby. My mother in law starts w/ "it's her first baby... You should speak to her ... She can guide you & ect....." As the woman walks in they begin to talk about her own pregnancy and then looks at me looks at her and the woman says "uour expecting...." I was full of rage! I wanted to storm out the room! I was so pissed off at her for not respecting my wishes! I have 4 older sister's who have given birth. When the times comes I will lean on them for support! Not a total stranger. I don't welcome people I don't know very easily into my private life & this being my 1st pregnancy/child I want it to be personal....
Since we've told her I'm pregnant I've been more stressed out! I feel I can't enjoy my blessing! She even showed up w/ baby booties the night of the party! I come from a family who believes in not sharing the news until at least 8 wks... Not buying items until we know everything is ok.... 
My mother in law also wants to plan our baby shower! Doesn't want me to have any input ... Expects me to simply "show up...." This doesn't seem right/fair! She says "you have enough to worry about.... Sit back and enjoy the blessings...." Wth! The days of holding a surprise baby shower and scaring the mom-to-be 1/2 to death I would say are over no?? 
My partner doesn't know how to handle this .... He doesn't want to dissapoint his mom and doesn't want me stressing. His mom and I are very much a like: 2 very independent women.... How do I deal w/ this! I want to be involved w/ my baby's celebration. I'm very big on celebrating and decorating ... I don't want tackie decor, locations and etc... I've waited so long for this pregnancy! I'm 35 yrs old! I feel powerless like I don't have a say and that's the worse thing someone can do to me!
I seriously need your advice! How do I deal w/ all this without hating this lady! Without losing my mind and not hurting anyone's feelings- primarily hers!