What would you do if you had a revelation that the woman you ve known for more than 26 years is not your biological mother. Considering the fact that she has not been nice to you either. She has always treated you differently and with indescribable hatred but over the years you ve learned to assume that she is just not a nice mother.
I need honest advice on what to do and how to go about it.

I'l be in a better position to give 'honest advice' if you give me a foundation to build on.
Please,tell us your story.

All you do is thank God that you are grown and have  your health. You can now move on with your life and be a better parent to your children. If you think is is going to be an emotional burden in your life you seek professional help and free yourself from anger and pain by forgiving the so called mother.

Argh.
I wud forgive my mum for abandoning/leaving me at a tender age.
The woman that brought me up,i wud still appreciate.2 mums for me then

huge sadness and huge relief at least now i know the truth. then comes the "what,how,why" questions. it would definitely not been an easy transition regardless of how i was treated by stepmom because all this years i have been lied to and have the truth hidden from me. its an anger,pain,stress,'the what ifs' etc i need to let out and if it is not something, i can handle with and within myself i would definitely seek outside help because serious and life changing things like this can definitely throw you off balance if not handled well. it wouldnt be easy,or be the end but a new beginning.

i would definitely pray to God to give me the strength to accept the things i cannot change. and courage to change the things i can