These situations are always quite frightful. I really think you could do with some legal advice and should approach a solicitor. If they are calling the police to make complaints, they are just trying to intimidate you and your solicitor should be able to deal with that, as it is no a police matter unless there is a breach of the peace or violence involved. You need in the end to have an agreement as to what each of your rights are, however hard it may be to achieve that.