Well, first let me say congratulations on your engagement! That is exciting for both you and your fiance.
Second, honey, you so did the right thing. What else were you suppose to do? Allow your 14 year old sister to be abused? Of course not. And I believe that any mother that has this going on in her home and doesn't suspect or know about it is either in extreme denial or disconnected from her child in an unhealthy way so as not to be able to notice something is going on. A mother that sides with the abusiving father has twice abused her daughter---------- she did not protect her from the beast nor did she side with injured and wronged person in the aftermath.
Do not fall for your mother's anger. It is misplaced. If you believe your sister (and what motivation does she have for lying about this??? )---------- this is all you need to give your heart peace. You did not wreck your family------------ you protected your sister. Bless you for doing that. It was very brave.
By the way, had an extended family member that was the older sister to someone being sexually abused by their father. She believed her sister and they went to their priest and told him. The priest that is bound to privacy and is well known to be friends with this family immediatly called the police and this man was arrested. He spent several years in jail (rightfully so). The mother of these girls was angry at the girls. Only because she could not carry on the lie of a life she was living. This older sister saved the younger one. And the younger one told her older sister because . . . she was the middle child. They had an even younger sister. She was saving HER.
Sometimes in life, we make tough decisions. That this was timed with your engagement is unfortunate. But I want you to gain peace in your heart that you did the right thing. I applaud you for it. Your mother will get over it. She will. If she doesn't . . . well, she is not acting very motherly.
You make a list of things that you need to work on for your wedding. If you want your mother involved, delagate and "give" the job to her. Then she is involved and yet you don't have to work on something together. Then you take over the things that you want to work on and work on them. There is no cloud over your wedding---------- this is you starting a NEW family. That is a celebration!!!! See it that way and celebrate.
I am the eldest of 5 and i was always the one to real with their problems my mum left when i was 15,not in the same league as your story but i can reate tohow you feel,just be there for your sister 100 per cent,your mother has just run to a man that has just abused her daughter,her morals and priorities are sick and wrong,you are a very lucky girl who has a man who is so stable and understanding,do what is right for your sister and arrange your marriage,whilst this is heartvreaking,your sister needs security and love and you and you partner can give it too her even more so when married,take her in and look after her and show her how a proper family is made love and help and encouragement is needed by all here.
You can't control how others react - only how you act. While you may be feeling some level of shame, guilt, or other emotion, don't let it affect your happiness. Proceed with the wedding, get to the happy stuff, and forsake everything else and start anew. Best wishes. :-)
You did not destroy this Family - if this Family is indeed destroyed Your stepfather gets the credit for that!!
You did the Right Thing so be Proud, be Very, Very Proud. I'm sorry Your Mother chooses a child molester over Her Daughters but find Your Peace and Comfort in knowing You did the Right Thing. Your Sister is a Little Girl and She needed exactly what She got from You - The Right Path is often the more difficult one - that's why Heroes aren't born every day. You are Your Sister's Hero. Your Mother is the weak one and I am Proud of You for being Strong enough to do the Right Thing.