My question involves a child custody case from the State of: PA

Long story short, my son is 5 yrs old his father and I were never married our son has lived with me and only me until 2009 when he got back together with his ex-wife and he requested shared custody he was granted every other weekend and two nights during the middle of the week. Our son has now started school and his father requested to have custody changed to Friday to Friday. I did not agree with this and offered that he see our son everyday after school until 6 or 8 pm and every other weekend. I offered several options but he only wanted the one week on/one week off. The mediator's recommendation came back that I get him after school Monday until Wednesday morning, Dad gets him after school Wednesday until Friday morning and we alternate weekends. This schedule is more confusing to everyone and it doesn't take into account the concerns and complaints I as well as my son has. For the past few weeks our son has been getting into fights, hitting other children, and being defiant.

1. Since father has remarried his ex-wife I'm on a need to know basis concerning my son. They moved over a year ago and I still do not know where he lives but my son is at his house every week.

2. I learned from my son that his step-mother or either her sister takes him to school instead of the daycare in the mornings. (However, dad said he was taking him to school even though I was paying for him to go to before and after school care)

3. I later learned from the teacher that they couldn't find my son one day because he caught the bus to daycare after school (which is what he was suppose to do) instead of waiting for his brothers to come get him to ride a different bus to their great grandparents house.

4. My son is constantly picked on, called names and afraid to tell his dad the things his siblings do to him because he's afraid that when daddy's not there or upstairs they will take it out on him and there have been times he did tell and dad either told him to stop being a tattle tale or didn't believe him.

5. He has wished many times that his stepmom would die or he didn't have a daddy so he doesn't have to go to his house.

6. Dad and wife adopted his great-nephew and is raising him as their son and my son gets yelled at for calling him his cousin instead of brother. However, my son knew him as his cousin before they adopted the nephew.

During all of this I have tried to encourage my son to enjoy going to his dad's house. He's voiced that his dad only cares about his wife and the children at him house but he's his child too. As his mother this hurts to hear how hurt he is and it's having an emotional impact on him. He's cried and become really upset saying no one asked him what he wanted and no one ever listens to him.

So my question is what is the best interest of our child?