Dealing with Reactive parent

I am a bonus mom to two wonderful boys now 15 and 12. I have been in their life for almost a decade. I have loved them like my own, kissed boo boos, all the games and practices and anything that comes along with loving kids. When I first was around we had the boys 90%of the time, she “had a lot going on” and had one more baby. So she only came around on some weekends for a few hours. Then maybe 6 years ago she started doing the 50/50 again one week here one week there. she and her new husband were very volatile where we would have times were we would have to drop everything and go get the boys out of a bad situation. She is very reactive and confrontational. Ever since I came around she has been very threatened by me, told the boys never to call me mom at a young age..fine no problem, I am a natural nurturer and loved them and made sure I didn’t “step on the moms toes”. My husband and I have had 3 more children and all the kids love each other and get along fine. They are the sweetest big brothers.
I can go on forever with things and events where she has been volatile and just being pure disrespectful, but she does so many things that effect our family without even discussing with us, takes time away from our week due to a “schedule mishap” even though it’s been the same exact schedule for almost 6 years.
Anywho she was discussing something in a text thread and I thought it was discussion she had a made a statement about one of the boys and I said “in my opinion it’s too much, but at any rate we need to just monitor him and see how he does” and then she out of no where goes.. “stay in your lane, I am his mother” I just said “I will always do what is best for the boys and if you like it or not we share children” and then I just stopped talking. She kept going on taking jabs at me, being very rude and disrespectful to someone who has done nothing but deal with her behavior and love her boys to death. I am not a confrontational person and I am just done with her.
I have no idea how to handle her at all the games, she sometimes ignores us or does fake chit chat. I feel like I will explode if I am silent any longer. Being a step mom has been the best and hardest thing just because of her erratic behavior. How do you all handle parents who only want you to “help” when it benefits her. She has made no effort to respect my position or feelings as a bonus mom.