A very good friend of mine finally figured out that her abusive husband was secretly being emotionally and verbally abusive to their kids behind her back when her 14 year old daughter reported him to social services. My friend put up w/ his abuse for so long, like a frog in slow boiling water, that she didn't realize how bad it was until her daughter told her. I do believe you, OP, and in hindsight, you're going to see it even more clearly. And as you see it, you'll feel more guilt that it wasn't more obvious to you, which means that acting now is critically imperative for your children's lifelong sense of security.
Also, from the way you describe your husband: being jealous of his own children, demanding hours of cuddle time and fears of abandonment, etc., he sounds like borderline personality disorder, which, unless you want to change and are committed to lifelong therapy, is very very difficult fix. Which means it's a very rare chance, like 99.99%, he's going to get better. We hear on MN women w/ shit husbands (cheat, hide finances, are rude, dismissive, unfeeling, lazy, cocklodger, etc.) yet these women will say, "Oh, but he's a good father," but you're not even admitting that, which means he's really, really bad.
Your five-year-old needs protection and your older DC need immediate action to reinforce what they've realized about their father. Leave him. Be careful as you do it, but leave.