You'd be surprised what people will do. I have really been through the mill with this. My ex-h has reported me to the police prior to every hearing, this week being no exception (we're back in court on Friday). So I hear you.
However, I digress..
So he's put in an emergency application, thinking your son is just going to be handed over. That is NOT going to happen. You have done a witness statement refuting allegations. Please ensure you in court that you have been unable to obtain legal advice. I can point you to Women's Aid and indeed Rights of Women...the latter is very hard to get through to but they will give you some free legal advice. You may find a local solicitor who would give you a free initial half hour. It is worth a try.
The process will be : first directions, the magistrates (likely to be them rather than judge) will want reports from Cafcass and indeed there will be searches for police/social services involvement. Cafcass will visit both of you separately. This could take a good few weeks. BEFORE the hearing, it is imperative that you inform your son's school/nursery/childcare provider that this is happening. If he is at school, you will have a welfare officer there who you can see. Please make an appointment. Also, speak to your GP and ensure they are aware of the situation.
Please also be clear, these people are not stupid. You can throw all sorts of allegations, you have to be able to provide proof. It's disgusting that he is telling your son he is not going to be living with you, that is emotional abuse and hugely unsettling for your son. How old is he? Depending on his age, wishes and feelings will be taken into consideration. My then 6 year old was "interviewed" and the Cafcass officer was wonderful with him.
The best advice I can give you right now is DON'T PANIC. I am not sure your ex quite knows what he's doing here..is he self repping? Sorry this is so long, but as I say, I am going through it myself so have quite a bit of experience now!