I'm going to weigh in with a different perspective.

To me, what you've described looks like a perfectly normal conflict where both parties have had something that matters to them threatened and they are fighting back to protect what matters to them.

It sucks to feel accused. It sucks to feel robbed. It just sucks, and when things suck it's hard not to react. We bring our worst selves to the table when we fight. From the sound of it you would like to bring your best self to the table.

You can do that.

Consider what you want to get out of this situation and then consider your options.

Ignoring the accusation is an option.
Lawyers are an option.
Responding, in any manner, is an option.
Writing a blog post about it is an option.

If you don't want to ignore it and you want to have a productive interaction, then ozarque has quite a few entries on verbal self-defense that might be useful.

There are also quite a few resources for dealing with conflict [1] [2]** which may be useful in figuring out how to approach and think about the situation.

**Not a difinitive or complete list. I don't have my bookshelf here at the moment.