I just need a vent and possibly a hand-hold as it's an awful situation. Apologies for the length! My DF's wife entered into a relationship with him when I was age 10. From the get go she was horrible and petty to me. Would refuse food/drink/toilet access if we were out and I got left with her. Often called me a little cow or bitch and told me I was in the way of her relationship with my DF. Prevented me from staying in my DF's home as a child and refused me access when I was pregnant and homeless as a young adult. She has never held down a job and my DF paid for her degree that she is yet to utilise whilst I was still a child. He never paid any child support and could never help with my living costs as he was supporting his wife. My DF wasn't really in my life until they were together so I have a lot of resentment for her from preventing me having a relationship with my DF. She proposed and emotionally blackmailed him into marrying her so she could be more entitled to his cash. My DF is scared of commitment and even his mother agreed he didn't want to get married. He is very well off and runs his own businesses. She is already down to have his entire life insurance payout and I doubt they have a prenup.
Now I have my DD, my 'step-mum' is constantly referring to her as 'my granddaughter' on socials and gives off a perfect grandma front when in reality she is a horrible selfish person. She is essentially using my daughter for likes and social appreciation. 'My' is very possessive, she could say 'our granddaughter' and I wouldn't have an issue. I know some people will say 'but she's your dad's wife so she is a grandma'. Not for me, I have probably only spent time with her on 5 occasions and she didn't really help raise me. She prevented me from living a decent life my childhood was so awful and poverty-ridden. They also live in a different county so have barely seen my DD either. She doesn't want children and is perfectly healthy to do so. My DM knows this info from my DF and relayed it to me. She doesn't see me as a daughter so why should she call my child her granddaughter? My DD has my last name too so they have the same name and it makes my skin crawl. I just wish we could choose our 'step-parents' sometimes