I'm going to be brutally honest.
Your in a lose-lose situation.
The problem is you filed for "visitation rights"
Now the husband will not let her see your step daughter
You can try calling the police. Honestly, they won't be able to do anything because your there for "visitation". They can't force him to let you in and will most likely they will say that this a civil matter or you need to go back to family court.
You will go back to court and file contempt of court
Right afterwards, her ex husband will go back to refusing to let your wife see your step daughter.
You go back and file contempt again.
Repeat until judge get tired of it and either judge places your stepdaughter in your wife's sole custody or in foster care. I know you don't want her out in foster care.
But you don't want sole custody. Or custody at all, which is why you filed for visitation right, correct me if I'm wrong.
The question is does the husband know he has this card to play.
My guess is yes, he knows
You guys are in a lose-lose situation if what I'm saying is correct.
Now if you had filed for "partial custody" even if just for a couple hours a week, the police can legally intervene if your husband refuses to hand her over since this is kidnapping. Whether they choose to or not is a different question though.
Then again, I can easily see your husband refusing to take your step daughter back forcing stepdaughter to stay with you with full knowledge that you either don't want that or can't do that due to work schedules,ect.