I suspect that your mental health is poor because you're married to this man. If not, then he's certainly exacerbating the situation - because you're giving him that power over you.
Please listen to the others (pretty much every single one who has posted!) and don't allow him to take your children to Iraq. He wants his family all under one roof - great; fine! Personally, I want world peace and equality across the globe - but that doesn't mean that I'm going to get that, does it?
If your children already have passports, please take them to someone whom you trust not to give them to your husband. In the UK, because you're married to their father, he has automatic parental responsibilities for them, so doesn't need your permission to take them out of the country - and given his underhanded methods of behaviour, if he has access to the passports, I'd not trust him to do that. One mother I know lost her son during a contentious build-up to divorce when his Middle Eastern father took him out of school early one day. He was in Iraq before his mother knew what was happening and other than when she visits once a year for a few weeks - she doesn't see her son. She's badmouthed about by the ex-husband, to their son and the older the kid gets... the more he's believing his father's lies, and their relationship is suffering. The boy's 14 now, and she says that she might only be able to see him for a few hours every other day when she visits later on this summer, because he's a teenager who wants to spend time with his friends rather than a mother he barely knows (and resents a great deal) anymore.
My oldest's biological "father" now lives in Dubai and for years - until she was 18, actually - I lived in terror of him trying to snatch her and remove her there. Even though we weren't together when she was born, he had no PR for her, and to the best of my knowledge has only seen her once in her entire life, when she was 3 weeks old (she's 27 now). I registered her birth at 4 days old, purely so that I could apply for her passport - to prevent him from doing so. He's very like your husband and I lived in dread of him taking my daughter just to spite me. Turns out, he married and had a few more kids over there - was abusive towards his wife (I know this purely because her sister tracked me down and begged to know what he'd done to me, to make me leave him - she was frantic about her sister, who isn't from the Middle East, and terrified that he was going to pull the stunt that he actually did 
). She divorced him, and he was "oh, let's co-parent amicably..." - until she had to go back to Italy for an emergency with a dying relative, leaving her children with him. Over there, the father holds all of the rights over the children, and so... he kept the children; wouldn't let her have them back. Apparently she's not even permitted to see them - and they were maybe 7 and younger when she left Dubai that time - because he's told their children two things: that she abandoned them because she no longer wanted them , and then, that she's died. According to the sister, he's told the ex-wife that it'd just confuse the children if she tries to see them, and that the older two (who were old enough to remember her) hate her for "running away" to her native country! I keep in touch, periodically, with the sister - hoping that my oldest's half-siblings have been told the truth (although I know him well enough to not be holding my breath over this!) and that their mother (who pretty much had a full-on breakdown when she tried to see them after burying the relative - already being upset about that loss, only to then lose her babies on top of it!) has been allowed just to see them, know how they're doing, something of that ilk. She was once very close to the rest of our shared ex's family, but they shut her out completely once this happened. And again, that doesn't surprise me. They got what they wanted - her children under their family's full control, all of hers essentially blocked from their lives. All she can do is hope that one day, her children figure out that she's not dead - and choose to see her. But again... I doubt that they will after years of his alienation and coercively abusive behaviour.
Please, @karisa282 , learn from these cautionary tales - and don't let it become your story, too. Go the police and report this abuser, take your children and run (with their passports) as far away as is humanely possible to get. Before it's too late. And when you're all safe, please divorce him and take steps to ensure that he cannot remove your children from the UK until they're adults. Chances are his plan is to divorce you and remarry over there, keeping your children as part of this plot (which his parents and he could have cooked up during their visit last month, let's be honest). But right now - you and your babies are at extreme risk of harm/separation.