Undiagnosed Paranoid Delusions

Hi, hope to get some ideas on where to start, apologies for the long story.

My partner of 9 yrs and I separated in Aug 23 and it was all very calm and amicable. We have a 6yr old and I have a 13yr old he has helped raised. He works away in mines and got himself a nice place by the water. Unfortunately about 3months ago he hit a bull on his way to work and totalled his car, thankfully he was unhurt. About 2 weeks after he found out the car was a write off someone stole his motor bike from his driveway. He was devastated, and was borrowing a friend's car until last week when he bought a new car. The problem is that about 2 months ago around when he had bike stolen he started saying that work had been spying on him through his phone and computer and he has like deep dived into this (has ADHD since a child) and I can see that it's gotten progressively worse, he now thinks his parents and sister are involved and 18 people from work. That they are adding code to his apps to record everything he does. He spent 2 hrs going through my pc yesterday and thinks I'm hacked or so he said and today he came round as the police have turned him away (was going in with evidence i think every week) so he wants to lodge a complaint and wanted to take my computer and go though my phone... in which I put my foot down and said no. He then started asking my why I was involved in this and asking me if I was getting paid to record him etc he claimed I met up with the fraudsters when I was on a recent girls weekend. The Dr has given him a referral to check in to a mental health clinic to be assessed as they think he is suffering from paranoid delusions but he won't go (although he says he will) because of this 'fraud' that he is being set up for assault, fraud, abuse etc. He left the house the other day and drove like 4 hrs away but left his house was wide open, he called and asked my dad to check it as he thought some people may have broken in. He thinks people are going through his house, works tracking him etc. I'm concerned about his safety, I don't want to leave kids alone with his and it's been mostly ok until today when he accused me of all this in front of the kids who where obviously upset by it. They just adore him and I just feel so helpless. I'm not so much worried for my safety as I don't think he would ever hurt us but I don't know where his head is at. I would love any suggestions or guidance on how to help him. Thanks so much 🙏