It is hard for kids. Some let the anger and fustration out physically some internalize everything.
In the end, the only thing you can continue to do is love them and be as understanding as possible. Never bash Dad...and continue to reassure them that you both love him. As he gets older he will form his own opinion of your H. Have you consider therapy for him?
As for your H's text. Maybe Kissak it is time for a nice healthy boundary. Maybe you should let your H know that you do not want these texts and if he sends them againg you will contact your phone carrier and have them route his calls to someone who give a chit. Boundaries Kissak. Stop allowing H to drag your butt back in. I am not saying be a prick...just that if you really do not need to get these messages or if they are too painful. YOU have a responsibility to YOURSELF to tell him to stop and/or do something for YOU that avoids getting these messsages.
Hope everything else is good and I hope business is picking up for you.
God Bless, Eric
"The difficulties of Life are intended to make us BETTER,not bitter". "Fear is a prison, where you are the jailer. FREE YOURSELF!" "Life is usually all about how you handle Plan B." - Jack3Beans