I am so sorry to hear this. Please do talk about this. I'd be devastated if my mom were to be alone all of a sudden.
however... you must support your mom and help her and cheer her up instead of letting the pain in. Try not to get involved and let her decide everything. Remember that it's her life!! Maybe your stepdad is simply doing through a phase... don't be judgemental.
You and your family are in my prayers - mind you, I don't do that all that often
!