Adopting Stepson; Bio mom PISSED I need support!!

Ca
Hey guys, so those of you who read my previous post know that I have a 4 year old son whom I've helped raise since he was 3 months old. Well, Dad and I are getting married and I plan to adopt my son legally after the ceremony.. I want to say my vows to our little guy too not just my SO. Biological mom (who we haven't heard from in months) caught wind of our plans and she met up with us today (first time we have seen her in years) and she FLIPPED out on me. I have never been called the names she said to me Infront of my son and my SO😞 She told me that this wasn't going to happen was screaming at me and I was a POS and my SO and I had to leave. Why couldn't she have stood up for her kid like this 4 years ago when she literally gave  him to us!! I'm heartsick and need support please❤️