My partner learned as an adult that he is on the spectrum. Learning to manage himself plus PTSD, and anxiety with depression episodes is alot to have on one emotional plate, so I can relate. There are an abundance of challenges here. You are not alone in this battle.
I try not to “undermined” him in front of our now 9yo, but I am not always the best at saying, “can we resolve this later, when their not around, or in bed?” It’s hard when you’re in the moment of trying to use gentle parenting, which sounds like more of your method, and your spouse walks in with their opinion even though they don’t know what’s happening in the situation. You try to explain to them, but they keep talking about how they viewed the child’s behavior from a distance, in front of the child. Then you’re frustrated, he’s frustrated, the kid is frustrated. It feels like your not only trying to parent your child, but your spouse as well. It’s draining, and leaves you feeling like you’re in this alone sometimes.
Gentle parenting is not for the faint of heart. Good for you for having patience and kindness for your little ones.
My spouse and I disagreed alot at first about parenting, which wasn’t an option for me. However, learning new methods of parenting, and what works best for your family can be challenging. He never knew what gentle parenting was before he met me. He was raised very authoritative, as was I, and we worked together to teach him why this parenting style is ineffective for many children. Therapy helps us often when we are having troubles communicating. He is also they type of person that from his own experience, he has found that researching on his own in order to further understand a topic or subject, instead of being told or explained, helps him mentally process changes and new information.
For us, we know that yelling and screaming is a trigger for him. No we can’t always avoid that with kids, they can get upset easily because they to are learning to manage their emotions. If I can, I try and deescalate the situation before he may become triggered. I try to remind him how children look for us to be their peace, even when a child’s emotional behavior seems out of hand. If we become overwhelmed it’s best to step away for a moment so we aren’t overreacting and possibly making what is a small event worse.
Often times we make time to all sit together and talk about situations and how they make us feel and what we can do to help each other when we are in need. It helps us listen and learn each other’s needs as we continue to grow as humans young and old. It allows us to communicate better as future situations come.
I hope you and your family continue to find the strength, patience and love you all need and deserve to build your bond. Breathe Mama, you’re doing great! 
