Custody/Visitation rights for fathers in California.?

My boyfriend is going through a custody battle at the moment, so far him and the mother of his child are agreeing on everything except whether or not I can be around his son. I know that whatever is going to happen is going to be in the "best interest" of the child. Well the mother of his son wants to argue that I am an unfit adult who just likes to party and drink, he knows better. I have a two year old of my own who I have physical custody of and joint legal custody. My question here is how much is she able to get away with? Seeing as that she really has no evidence that I am a bad person. I have no records of violence, alcohol or drug abuse. I support my daughter and myself on my own. Let me state that I am 21 and my boyfriend is 25, we have been together for a year and this last year has been great with him but hell with her because of her constant drama. We are making future plans together so I know that eventually I will be around his child, I just want to get a take on what could happen with his case. I have respected the mother of his child's decision for me not to be around their child thus far, but now my boyfriend and I have discussed that it was time for us to meet. So I'm now curious to see what is going to happen with this situation. They have temporary custody for a month I will not be allowed around their son but their next mediation they will discuss what will happen. What can I expect from here on out? With the judge and mediation?