I am the mother of two minor children that were conceived during a existing marriage! Both parties separated and the father hasn't seen, called, nor supported the children in anyway... is this child abandonment?

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Second, did you read the thread you posted to? The answer to your question was in that thread. https://www.askmehelpdesk.com/family-law/child-abandonment-read-first-364259.html#post1793644

You are asking the wrong question. You should be explaining what you want to do about the situation and asking if you can do that.

It can be used as a reason to file for divorce, to file for child custody and file for child support.

So what have you done in court yet.