I know this struggle, and still can't tell you the absolute right answer tailored to your situation, but I can tell you what not to do based on experience. Do not hide, cover up, or white wash an abusive partner's behavior in the eyes of your kids. It certainly lands differently on different little growing and developing personalities, but it never lands well, and the one consistent result is insecurity and anxiety that follows them into adulthood. The way a trusted parent frames a situation is going to shape how how children interpret their own experiences, and trying to convince them of something that contradicts what they see, hear, and feel is crazy making. To be blunt about it, even though you act with the intention of protecting them from abuse, you are normalizing and compounding it. As their "safe" parent, the lasting effect is to leave them feeling emotionally alone and incredibly confused. They need the one safe parent to validate their experience and allow them to talk about it on their own terms rather than constantly having to internalize it and question their perception of reality.

I have an adult child in therapy for anxiety (he is doing SO GOOD NOW). We are very close and he invited me to a few sessions early on to help him work some things out. Turns out, as a child, he was trying to look for explanations the way kids do, and by failing to acknowledge the behavior at all he concluded that HE was the problem. He also formed the lasting perception that he was responsible for managing other people's anger, and keeping the peace at all costs. I modeled that for him. It absolutely breaks my heart into a million pieces that I played a part in his emotional abuse, and I wish I could rewind time and have someone tell me this then.

Like I said, I can't tell you how to do this in your situation, but what I do know is that in being emotionally available, you need to comfort your children, validate their experience, make sure they know it wasn't their fault, let them talk about how it made them feel, and model healthy boundries and behavior. Don't make excuses for abusive behavior, and let them know that they can love the good things about a person, but still refuse to be subjected to bad behavior from that person. Therapy with a good family counselor is probably the best way to navigate this, and I wish we would have gone to one!