Partner jealousy

I am in a new and wonderful relationship that I’m very happy with. We’ve been good friends for some time and I’m also friends with his ex (who I love, and she is wonderful) and they’ve remained good friends since their breakup last year. And I’ve been feeling a lot of jealousy over their closeness lately. I know the problem isn’t that they’re still friends or that they still visit. I want them to have a good friendship and I want her to be in our lives as a friend to both of us. And I know that my own feelings are not coming from the external situation but my own inner landscape.

When I try to find the thoughts that the feeling of jealousy is coming from, I recognize that they’re not thoughts I actually believe (T: I’m not as significant as she is because they were together for so long …ie: I’m not special or important to him). But even though I know I don’t believe those thoughts, I still have feelings of jealousy come up. And I expressed it not so gracefully a couple of times and it caused some problems with us about a week ago where he lied to me and didn’t tell me he was going to visit her. I became very upset about this and we had a really emotional conversation about it. I see how my emotional reaction made him feel uncomfortable about sharing with me their maintained friendship. And I don’t want this to create more problems like that in our relationship but it feels like a bit of a double-edged sword where I feel tender, he doesn’t want to hurt me or cause problems so he hides it, then I get upset about him hiding it.

How do I handle these emotions so that it doesn’t create more problems in our relationship? I want to feel good about them hanging out and spending time together but right now it feels icky and I feel jealous about it.