I'll start off by saying I don't want too. I've had enough and I've left.
However myself and exH went through a rough patch I lied for a while and then we tried to reconcile however he began suffering with paranoia.
He has 'thoughts' (his words) that I may have slept with someone else during our time apart. I didn't. During our time to reconcile, he still had thoughts that I was up to something. I wasn't.
Let me just clarify that I have done absolutely nothing with no other man since the day I met him. Never cheated on anyone in my life and never would.
When he has these thoughts, he lets me know about them. He becomes either cold (I can tell he's thinking something over something I've said) or he becomes quite nasty. No name calling but the way he speaks to me is not on.
The last one was 2 nights ago. ExH is working away. We have 1 dc and I was really struggling to get her to sleep in the heat so I took her for a late night drive which worked a treat. As I pulled on the drive, exH called me. Which was weird in itself to call me at that time but he had sent me a message which I hadn't responded too as I'd been driving and not seen it.
I answered the call as I pulled onto the drive and explained I had taken dd out for a drive. He's reply immediately was to snap at me. He said 'oh course you were' and 'I won't tell you what I'm thinking right now'. I can't remember what I replied with but I was angry and he hung up on me.
What an insult. He clearly thought I had been out with some bloke or something. I took a picture of dd fast asleep in the car in just her pull ups with it being so warm and sent it to him. The reply I got was 'thanks for being so understanding' in regards to his paranoia.
I haven't spoken to him since. Ignored all this calls and texts. Which no doubt will be driving him insane. He hasn't moved back home officially thank goodness. Though he absolutely hates the fact that I live alone (apart form with dd). My mum stays with me quite frequently and he loves it when she's there (as it means I won't be having any random men round 
) but when she's not here, he gets so anxious.
But I am sat here wondering if this can be fixed? When we get on, we are great but there is no chance I'm putting up with this for the rest of my life. Im starting to walk on egg shells around him, thinking i might say something which could trigger him. He says he trusts me but can't help his thoughts which makes no sense to me and I dont have the energy to try work it out.
Also just to add that typically he did sleep with someone else in the time we were separated. I've never classed it as cheating. It's not great but it's something I was willing to get past to save us. It was just a random one night stand.
Just to repeat - I have not and never would cheat on him! Should have that tattooed on my forehead!
How would he even try tackle this? It just seems pointless to me. Plus - it's not my problem! It's absolutely not for me to fix.