Need some positive vibes - I feel like I'm loosing my family.

I'm an imperfect Mum, though I'm not a bad Mum. But at the moment I am really doubting myself.
6 months ago my ex decided to keep one of our three children after a scheduled visit. For the 2 years before this I had care of them for 12 nights a fortnight and he had them every second weekend.
I did not agree with his decision to keep our son, but at the time I didn't feel I had any other choice. For 6 months my only contact with my son was quick visits at the school, (I didnt want my son to be stuck in the middle of a tug of war, so decided that I would get him back through the legal system instead of 'snatching' him from his school). I got given bad advice from a legal advice helpline, who told me that because he wasn't in any danger that applying for any orders to have him returned wouldn't work. I have since found out that I could have applied.
I applied for legal aid in January, paid my contribution to mediation in February, and finally went to mediation at the end of May. We agreed to visitations, but will be going to court for custody.
During this time my ex has been trying his hardest to make me into a monster. He tried to get a DVO on me, for the purpose of preventing me from seeing my son. It didnt work btw, as he had nothing to base it on.
But at the moment he is trying to get custody of all 3 children and is trying to make me look as bad as possible. I feel terrible.
Id really like to hear from other IM's that have been through similar and won their children back through the legal system, I really need a little ray of hope at the moment.