Is there anything I can do to prevent his threats of eviction and hateful emails at this point? My ex told him to go ahead and start legal action. But what legal action can actually be taken?

This is the email that the landlord sent me yesterday, I questioned the part where he states that he will give my ex possession of the house. That's what prompted the email I posted previously....

"Carissa & Jon;

Has there been any discussion of settlement between the two of you? On behalf of the owner i submit the following;

Jon, Carissa has not responded to my proposed offer of settlement.

Carissa, Jon has offered surrender the possession of the house to you.

Carissa, are you prepared to accept the full responsibility of the lease?

Jon, are you willing to surrender leasehold rights and the security deposit to Carissa?

Carissa, Now with Jon's proposed settlement, I can offer you a new lease on a limited basis. Until February 1, with a security deposit, I can offer to complete a new lease with you. Jon would have to agreed to surrender his claim to a security deposit refund or you would have to pay a security deposit of your own.

Without a mutually agreement that i am trying to broker, Jon has the right to claim possession and can access the property at anytime. "Time is of the Essence" to claim your exclusive right of possession.

Carissa, Please direct us how you would like to proceed? "