It would be a reasonable possibility that she did that. I doubt it was healthy though if she did that. On the other hand she had a very supportive and understanding inner circle and of course her future husband River that supported her and gave her a great friendship. I have a feeling that Moon loved the fact that she found away in which she ruined Toffee's unbeatable tough guy aura. Maybe she considered it a fitting punishment. After all he was done with being influencial in the monster army after he got hit by that spell. Maybe Moon wanted to make Toffee feel what it's like to lose something that is really important to you the same way he took away her mother.
I don't approve of it but I do get where people are coming from. Usually the people that think that way have a certain mindset about these specific people are good. In history those people helped us grow stronger and more prosperous. So they are good. And when they discover people that have completely different view points and ways of life that they cannot comprehend. Then either the ignorant kind of racism kicks in like saying you want to help them to a better way of life(specifically your way of life). And then their is the pure brutal form of racism that thinks those people are barely above animals so we don't have to treat them like humans. If they help us fine but if they are in the way get rid of them. I can barely even begin to conceive the culture shock the Europeans must have experienced when they met the Native Americans. Chances are the words backwords little heathens and savages were dropped several time.
I am guessing that he would realise the error of his way in the end. And if he doesn't then in the end he will turn anyone who cares about him against himself. So if he stays the yerk he was he loses everything and if he betters himself he will win. Pretty simple for me.
You need to remember that Moon is a Butterfly. If they want something it will happen. No matter if they have to move realms and dimensions it will happen. So not even Marco's denseness could protect him if Moon decided she wants Marco as the next king of Mewni.
I am happy to hear that I will have more time. Then I can study for this exam I have in 12 days.