What can i do?

firstly remember you are not to blame for the way your mom feels. It sounds as if your mom has problems with moving on with her own life..she may be feeling betrayed by your father, for moving on after their relationship failed, she may even feel that she still loves him deep down and that is why she behaves as she does, your father shows you love and attention when he visits but does not pay any real attention to your mom, in a way she is resentful of the attention you are getting from a man who was once a big part of her life. all you can do is tell her you love her, she needs to be needed, encourage her to make new friends, to have the occional night out but also to believe that she is lovable and out there somewhere some one is waiting to love her again... because there is life after divorce, she just has to believe it. I hope all works out well for you. take care.