Hi Motowaves! Your husbands primary responsibilities are to you, his daughter, and yours (to which ever degree works for your family). It sounds like his wife is still trying to keep an attachment to him through your stepdaughter.
Boundaries are important. It seems she's crossing them and your husband feels uncomfortable rocking the boat so he just goes along with it. Pretty common. If he stops indulging her, she becomes high conflict. Tough situation you could not have anticipated when you chose to marry him and parent his daughter with him. If it bothers you, it's too much. That's it. You have a voice, a very important one:). It's his job to respect your boundaries and work with you to establish them. If his ex wife is uncomfortable, that is her problem.
Some women move on after a divorce and truly respect their ex husbands choices when it's time to move on, others do not accept the finality of divorce. This is up to him to make clear to her, and not use your stepdaughter to keep the attachment strong.
Download the June issue of Stepmom magazine...is the Father's Day edition and I highly recommend it.
Do not apologize for having boundaries and expecting your honey to respect them;).
As both a stepdaughter and a stepmother, I can assure you your stepdaughter will also appreciate all you can do to clear the muddy waters with her mom as she grows up, and everything you and your husband do to keep your marriage strong.