IMO these are idle threats, they all say the same things. It's like they are reading from the same book.
First of all there is a record of his arrest, secondly in Florida you (as the mother)would really have had to do something real, real serious before the courts would not award custody of the children to the mother.
See a family law attorney, don't listen to his BS, he as an addict has the attention span of a 3 yo, once the wheels are rolling he will most likely move onto something else.
Protect those children, you are their future.