Doormat, it sounds like you have been through the mill a bit. I can't believe that they would kick a 3month old. What did you do? I can't imagine what I would do ( well, I probably can, and its a bit scary).
I hope that what has happened to you doesn't happen to me, its started to happen already (lying about things I've suposedly done) and dsd is using her new found 'power' to its full advantage, dp does realise that she is "seeing things differently, and mistaking things I say/do as having a go at her". BM is meanwhile going mad because she thinks that her dd is scared of me and is unhappy when she comes here. DP is spending a lot of time explaining to dsd that she has misunderstood, but she just turns on the waterworks and Daddy never really has the heart to tell her off for exagerating things.
The weekend (apart from the texting thing) she was in our kitchen complaining about how cold the floor was, so I said "Go and put your slippers on then". She stomped upstairs with the hump, dp called her down, she refused, dp got a bit annoyed with her and 'insisted', dsd came down in tears saying "Squirrel was horrible to me, she shouted at me"! I can honestly say I didn't, dp was there and heard what I had said to her, so he said that I hadn't, he was there and heard what I had said. dsd cried even harder so dp gave her a big cuddle and loads of kisses and said "well, never mind".
And I get left feeling a bit cheated because she is being a drama queen, making me look like the wicked stepmum (which I can't describe how that makes me feel, I am trying so hard with her) and she gets more attention (which in my opinion is what she is after), she then goes home and tells BM all about how horrible squirrel is, then we get a tirade of rantings from BM and all I've done is try to and be friends with her (dsd). I know dsd would love it if dp and I were to split-up, she would then have Daddy all to herself.
I feel that if she were biologically ours these problems just wouldn't exsist, its so hard being a stepmum sometimes.