I was also going to ask whether you have a Solicitor involved. My concerns also re mediation are the same as Cogito's. I think you could well find this whole exercise a complete waste of time due to his overall non co-operation.
To use mediation is to subscribe to the mistaken idea that abuse is related to "misunderstandings" or lack of communication. If discussion and compromise, the mainstay of mediation, could help in any way most domestic violence situations would be long ago resolved because victims of abuse "discuss and compromise" constantly. Mediation assumes both parties will cooperate to make agreements work; the victim has always 'cooperated' with the abuser; the abuser never cooperates.
Mediation can be and is ordered by judges/courts, as can counselling and mental health evaluations. They are tools in the abuser's arsenal to be used against the victim as often as he chooses. In order for mediation to work and to not make situations worse the parties involved must have equal power and must share some common vision of resolution. This is clearly not present when domestic violence has taken place in a relationship.
Mediation practitioners must be alert to the need to interview partners separately with specially designed questions in order to determine if abuse is or has been present. Many domestic violence professionals can train others to screen safely for domestic violence. To not do so risks unsuccessful mediations, at best, and increasing the victim's danger by colluding with the abuser, at worst.
A person who has been terrorized by an abuser is not free to participate in a mediation process with him, even if the mediator(s) assume or believe that they "understand". Being truthful about any of her needs or experiences in the abuser's presence or proximity practically ensures that she is in more danger later.
The mediator is left with a no win: either the victim's danger is increased, or she is not fully or truthfully participating, or both. The well meaning mediator may actually encourage the victim to feel safe enough to share information that could seriously compromise her safety. In any case the whole intent of mediation is lost.
To engage an abuser and a victim in a process that implies equal responsibility is damaging to both. The victim is once again made to feel responsible for the abuser's behaviour, and the abuser is allowed to continue to not accept full responsibility for his behaviour choices.