I hope you are safe. Whatever help you need for your condition, it sounds as if this relationship isn't helping you. If the friendship was platonic and he cared about how distressed you were (worrying about being paranoid and having an episode) then why wouldn't a loving partner immediately set your mind at ease by being totally open about the communications he is having rather than being secretive and giving you genuine reasons to be suspicious?
The thing is, even if they haven't crossed the line by the content of the messages and phone calls, the sheer quantity of them when he is in a relationship with you suggests that he's putting too much time and energy into that relationship.
Just because you're paranoid doesn't mean he isn't having another emotional affair. 
(Sorry, I know it isn't funny, I hope you are okay x)
If he was telling the truth about you being abusive, jealous etc, then why would he want to prevent you going to your mum's? Why would he be threatening to 'have you committed'? I don't think he's the victim in this, no matter how hard it is to support someone through serious mental ill health.
That said, I think you are right to get in touch with your psychiatrist and to seek help to get through this crisis. It may be that a short stay in hospital may be helpful to you to keep you safe and help you get access to extra treatment and support that you would need to wait a long time for as an out patient, and give them a chance to get your medications right. But you can discuss this with your psychiatrist, it wouldn't be like 'being committed' as a punishment for telling your husband to end his emotional affair.
I suggest that you also tell your psychiatrist about H's emotional affair, how he dismissing your right to be suspicious by telling you its just your paranoia, how he's threatening you with 'being committed' and accusing you of being abusive. Talk over with your psychiatrist whether these things might be exacerbating your illness, and explore the idea that he might be gas lighting you (trying to get you to believe you are more ill than you are in order to control you).
Please don't harm yourself. Seek help from mental health professionals and the Samaritans I know that you are feeling overwhelmed with everything at the moment and it must be really distressing. But it is a crisis. It will pass with the help of treatment and you can be happy again, honest. If your relationship is breaking down then that will be another source of stress, so lean on the professional services rather than your H to help you get through it.
Take care of yourself. Stay safe 