We need more information to give us a better idea what is going on.
Do you know why your husband gave his sister Power of Attorney and not you? When was this Power of Attorney signed? What are the reasons why his sister won't let you visit [if you could afford to go]? And why won't she give you any information regarding how he is doing? When did your husband go into a facility, was it recent or some time ago? Were you unable to take care of him, thus he needed a higher level of care?
I'm not sure I understand either. Is your husband living out of town?
The facility won't give you information because he (or his POA) has signed papers stating that they are not to give out information regarding your husband. Why has your sister-in-law taken all of this control over your husband?
What will happen if you go to see him? (My experience, anyone can walk in off the street and go visit whoever they came to see at a NH. We sign in at a desk, but there's not exactly any security guard saying 'who goes there?'.)
Do you know why your husband gave his sister Power of Attorney and not you? When was this Power of Attorney signed? What are the reasons why his sister won't let you visit [if you could afford to go]? And why won't she give you any information regarding how he is doing? When did your husband go into a facility, was it recent or some time ago? Were you unable to take care of him, thus he needed a higher level of care?
The facility won't give you information because he (or his POA) has signed papers stating that they are not to give out information regarding your husband. Why has your sister-in-law taken all of this control over your husband?