I haven't read through all the posts so I apologise if I reapeat things that have already been said & I apologise too if I go off on a tangent.
I have, at best, a very strained relationship with my mother. I too lived my Nana for a while & our relationship remains a strong & loving one. My relationship with my mother is far from that. I was an unplanned baby when she was 19, she's been married 3 times & has 6 other children now. I have spent most of my life feeling unwanted & rejected by the person I have wanted to love me most. Even after all this time, all this rejection, all this hurt I still long for my mother to be some kind of mum to me. I would give anything to hear say 'I love you' or 'I'm proud of you'. I know that she will never change, our realtionship will never change yet still I build up my hopes for them to be dashed, that is something that very slowly I am learning to except but also I know our relationship won't survive much longer & very soon I have no doubt it will come to end & for good.
3 years ago I had my DD, she was very much planned & very much wanted yet when she was born I felt I didn't want her. I felt completely overwhelmed by having a DD & wanted to run away as fast as I could. I did everything that I was supposed to for her, bathed her, fed her etc etc but I never really held her, something I'll never be able to change. DH was (is) besotted with DD & they have an amazing relationship & so I was happy to step back & let him be everything to her. (I was also diagnosed with PND when DD was 4 weeks which as you can imagine didn't help matters)
When my DS was born a year ago I felt instant love for him, I bonded with him immediately & felt so, SO different with him. I really felt like a mum. It was then tha realised that if I wasn't careful I was going to end up like my own mother & have an awful relationship with DD & that one day I might loose her.
It took me a long time to pluck up the courage but eventually I took myself along to my GP as I wanted things to change, I didn't want my DD to feel the way about me that I feel about my own mother.
I'm currently going through counselling & CBT to try & change things for the better. I'm trying to hard to break the cycle & I'm learning alot through counselling about why I cat & feel the way I do but slowly it's changing & DD are getting closer & learing more about each other. I'm positive that in time our relationship will be how it should be & I would have broken the cycle.
What I'm trying to say is I can empathise with your situation. I can also empatise with feeling different towards your DSs & your DD. However I'm not sure that having DD living elsewhere is going to help, you need to work through your issues & I think living seperately is going to make that very hard. How does your DH feel about your DD living with his MIL? I know you say that DD misses her Nan but surely she must miss her Dad & brothers & her Mummy too?
Have you spoken with anyone like a GP or HV about how you feel?
I don't think you're a monster, I think you're a Mummy/Woman going through a lot.