Remember we hurt the ones we love, I too have a daughter with Bipolar and I know that when she lashes out at me it is because she feels safe with me. I think children with Bipolar have emotional disfunction, they do not know how to express what they are feeling in a constructive way. My daughter is now Nine and it has taken a long time for her to learn how to express herself with words rather than actions. We still have many problems with her but they are minimal compared to when she was five, she is now able to say things like "I am in an angry mood and I dont know why" this gives us a chance to help her through the moment and hopefully avoid a major meltdown. We used to live with daily meltdowns now she may be irratable but we nearly always avoide to extreme meltdown. I hope this gives you some comfort, I know how hard this is, get some therapy as I beleive this has been paramount in helping my daughter understand that her behaviour is unacceptable even though the reason for her behaviour is not her fault, its all about managing the illness with the behaviour, this much I have learnt. My thoughts are with you.
I've been thinking about this all day and I don't think he hates you. I think that he is just having a tough time and for whatever reason, he focuses his frustration at you because he can't express himself correctly. I agree you need to talk to his psychologist about this. He is so young and with bipolar that must be so hard. I have 2 sons, so I understand that you want him to love you. Please keep us updated, I hope you find an answer to why this is happening. :(
I would think that it would be best to discuss specific parenting techniques with a child psychologist. Behavioral therapy might help solve some of what he is doing as well and you could ask about that.