Contract fault being harrassed by other party

I was contracted to do some online work with a company. This required purchasing some online templates and online work. The contract specifically stated an upfront cost of $300 would cover the cost of the templates ($150) and a commitment fee ($150) for work until invoicing. The work has been extremely difficult and the completed project is approximately 6 weeks behind and I am not sure when completion will be. I have also had a death in the family and a severe illness of my own in this time.

I am now receiving very threatening messages from the husband of the lady I contracted with. I offered to deliver the templates to them and refund $100, apologizing for the inconvenience. The harrassing calls continue and I feel a physical threat is being implied.

My question is: What position am I in? There is no explicit completion date listed in the contract. I feel that my offer was completely fair considering I have put nearly 50 hours of work into this project. I also did some other on-site computer work for them that would be invoiced at about $65, but I have not brought this up at all. What should I do?

I am located in Indiana. Thanks in advance.