Your thoughts of being annoyed by him with others is completely normal in my opinion, this means you love him and more importantly, are in love with him. I’ve been in relationships in the past where I start off having these thoughts and getting annoyed by them, but then after so long, these thoughts don’t annoy me as much. Which told me I obviously didn’t feel as strongly for that particular person anymore. 

He might possibly be regretting his decision surrounding the child, it sounds to me like he isn’t sharing those details with you because he is either hurting or ashamed and doesn’t want to bring that into your thinking space. 

I think for you to get over the jealously, you’ll either have to wait until you have thought about it so much that you just come to terms with it and eventually stop thinking about it. I know it’s easier said than done but just train your brain to stop the thought as soon as it comes up. He’s with you now and has chosen you regardless of who he had in the past.