I am both a step daughter and a step mother - both can be difficult situations at times, for all concerned, but I think that "Acceptance" is the way forward .
Like, dislike, love, hate, jealousy etc cannot be allowed to dominate if you love the person who is piggy in the middle (in my case, my father and my husband).
In fact, having had a wobbly start I realised that my dad had actually made an excellent choice and I could see why he loved my stepmother so, despite expressing hatred for her when I first found out my dad was leaving my mum for her. I was angry and embarrassed and all sorts of other feelings, but my amazing stepmother weathered it all and stayed true to herself and with acceptance and respect she became like a 2nd mother to me and I love her to bits.
My step children are still a work in progress however but that's another story.