I think you maybe need to pump the brakes a little. Your ex was your fiance, not just a gf, someone you thought you'd spend your life with. Also, this new woman has a special needs child with another man. I know you say its no big deal now but easier said than done, and I'm not even talking about the special needs part. Its not easy at all. Nothing wrong with re-connecting but don't rush from one failed relationship to another. Seems like the new girl is sort of demanding also.
So, so you think you can tell Heaven from Hell,
blue skies from pain.
Can you tell a green field from a cold steel rail?
A smile from a veil?
Do you think you can tell?
And did they get you to trade your heroes for ghosts?
Hot ashes for trees?
Hot air for a cool breeze?
Cold comfort for change?
And did you exchange a walk on part in the war for a lead role in a cage?