When your H gets back in the picture, you need to Detach Big Time! He does seem to be reveling in this new found life of his and hasn't had to feel any of the emotional pain that you have endured.
Being away from the kids is one thing but having to raise them on your own and in the absence of a supporting S is doubly hard. He needs to experience this on his own for an extended period of time for the reality to set in.
"H left a little teary eyed after some loving good byes from the girls."
Good! He needs to start feeling the hurt that you have been experiencing.
"...but I want you to know I intend on being a big part in our girls lives and am willing to do whatever is needed."
...except of course being the H you deserve..... jerk! Sorry, couldn't help myself.
"...if you wanna take a vacation after I'm back, please let me know."
This is him throwing you a bone and nothing more. He's behaved terribly and wants to make it up to you. Yeah right! This is exactly like my W who says "she has given it a lot of thought and she really MUST take another long weekend with OM. Oh, and you know, you should do the same... you deserve it!" BARF!
"Anyway I have no idea how to reply."
I think that you should not acknowledge any of the BS contained in the email. Simply say something like "I'm glad you had a good time. We'll talk more at another time." And leave it at that. Nothing more. Let him feel the sting of your non-response.
Then find a way to detach when he comes back in the picture. That's the best advice I can offer at this time.
Hugs and kisses!!
Me51 W53 S17 S14 M22 T25 Bomb-9/11; A-11/11; I move out 11/11
It's easy to find our bottom, it is our top that requires cultivation.
Every rough spot adds to our emotional constitution. -Barney Fife