Please help me help my husband

I wondered if someone would be able to help me please?

My husband is only 22 but was diagonised with ADHD when he was about 12years old, he was on concerter for about 5 years, he then came off them just before he met me. I have always knew he had adhd and it never bothered me as i learnt to deal with his outbursts, tantrums, lack of concentration and inappropriate comments he would make! 

However over the last year it has got progressivly worse.  When i was pregnant, he was over the moon and would wrap me up in cotton wall, however as the pregnancy progressed the more nervous he got and the more outbursts he would have.  We went to the docs to try and get him some help, ie get put on his mediciation again or see a councellor, however they just gave him depression tablets and that was it!  I have since had my baby boy and he is now 6months old.  My husband totally adores him and loves him so very much, but he just cant deal with him, when hes crying or screaming, and sometimes shows no interest in him at all! When hes crying he would rather watch tv than pick him up and sooth him.  It came to ahead last week, when i was trying to calm him down after an argument with my sister, however he got slightly violent with me and slapped me on my arm!  He has never never done this before and immediatly appologised, but i wasnt having any of it and threw my rings at him, telling him to get out, he then took our son and walked out (normally he will just go for a walk and calm down and i normally just let him)  however he has out son and the mood he was in i didnt want him to hurt our son, so i followed him, this just wound him up even more, and i was aware of this, but kept following me, he then pinned me against the wall by my jaw and told me to leave him allone.  I knew then i had pushed him too far and walked off!  He came back after 5 mins, however when he came back he dumped our son on the bed went into the kitchen and started taking tablets with allchole and cutting up his arm, and smashing glasses everywhere.

I told him he needs to get help, and i will support him if he does, as i know hes not well! so i went to try and book an appointment with the doc today to try and get him some help and he refused! 

Im at my wits end, and i dont know what to do to help him!  I know hes not well and im willing to help him, but if he doesnt want to get help, then im scare of what he will do next to me or even our son.

Please help me! and suggestions would be appreciated xx