Speaking from experience, it is very hard work after a divorce. I’ve been divorced for about six years now, and still have things pop up now and then with my sons. My advice would be to try very hard not to speak ill of your ex in front of your son, and do the shit talking with friends privately instead. Some days I bite my tongue harder than others, some days I fail, but the effort is worth it for your son’s sake. Wishing you so much good luck as you navigate this new normal with your son. He’s lucky to have a responsible parent looking out for him!