
Sorry but I do think you are over reacting, your m-in-law is more than likely still grieving. Please try to remember that she is not only grieving her son's fiance. But possibly a good friend, someone who she had grown to love and respect just like she may do you. And also the future, of what was planned and obviously didnt happen.
She has every right to have her picture up, just as your fiance does, if he so chooses. We dont stop loving someone when they die, we learn to cope, to change our lives to adapt to living without that person, to start a new life. But that doesnt mean we have to forget our past lives.
I lost my Husband 3 years ago, I still have his picture up and always will. Regardless of who is in my, As he is part of who I was and who I am today.
You know I dont really get on with my in-laws, I'm not really included in any family gatherings etc, We only now keep in touch because of my son. But they still have our wedding picture up.
My mum still has his pic up as well.
You do really need to try and acccept this, and move on. Her son loves you now, and wants to marry you. His mum will accept that in time. And dont worry about the lack of congrats from her, Every time me and my husband went to tell his mum and dad of news ie engaement, pregnancy marriage etc They groaned at us lol.
Alix