Tenant says I cannot show the house (Michigan)

[Robert M.]

Hello,

I have a tenant that has an expiring lease in at the end of August and she doesn't want me to show the house while she is living there, even though my lease says otherwise.

Back story: About a 2 months ago the tenants came to me saying they were planing to break their lease early because her boyfriend is moving for a new job. However, I do not allow people to break their contracts early but I indicated that I would work with them to find a new tenant if they were willing to let me show the house so I wouldn't lose any rents. She said no and gave a bunch of reasons. I have all this in writing. I only asked then because it was > 45 days until her lease is up. After that I hadn't heard from her in awhile and when I did contact her she said they were going to stay in the house until mid-August (which basically is staying until their lease is up).

Present:

My lease states that I am allowed to show the property 45 days before the lease comes due. Therefore, I am in the process of looking for new tenants.

This morning I sent an e-mail to the tenant indicating that I plan on showing the house this coming Thursday to someone. She replied saying no, giving reasons as stated before. 

Before I needed to get her permission (> 45 days), but now I have the right to show the property - even if they are not home. I do not think she knows this, but it is in the contact she signed.

Now, what can/should I do?

In Michigan, am I not allowed to enter if she has already said no (not an emergency)?

Can I just oblige by her request and take their security deposit for that lost month (Septemeber)?

If I am planning on taking her security deposit, do I need to let her know this?

Recommendations?