kat,
i am so sorry for your kids.
and im sorry you cant physically help them.
i have no advice.
i am baffled on some of this stuff myself.
Maybe buy them all webkins, you sleep with them while the girls are with you (the webkins) then the girls can take the webkins to thier dad's. when they are sad, they can hug the webkins and know they are getting a hug and love from you.
i dont know...it's a thought.

your kids set aside,
LOL and HAHA! that your stbx is
having fights with the town wh oo that he
so stupidly choose to shack up with!
and THIS is BEFORE that baby is born.
GIRL! there are going to be some
nasty fireworks in that house over the next few months.
i hope your [censored] stbx is miserable as HELL!!

(but, im sorry your kids have to suffer because he's an idiot)