Friend turns into Bride from Hell

I have a friend who has lost her mind. It began with her obessing over becoming engaged to her boyfriend. It was all she could do to make it happen. Everything related back to the fact that she was relationship obsessed and wanted to get married. You would ask how others were doing, and she would respond with how their relationship with their boyfriend was going…. and gossip about the turmoils of the relationship.

Anyhow, the day came when the guy popped the question to her (finally! we could all take a breath and a sigh). Now, she has asked me to help her with her Announcement of the enegagement. I agreed and said I would do it free of charge, since she is a friend. It has been 2 months, and this is out of control! She has gone off the deep end and is straining our friendship. We are almost done at this point, (6 rounds of copy later). But the constant emails at my work, along with phone calls about copy change and envelope sizes when I'm in meetings, the inability for her to understand that I have a job (which she does not) and now she has over stepped the line twice, both times with angry emails about how I don't give her enough attention, threatenging that she will just finish it herself. The final straw came last week when after much discussion, she could not find an envelope size that she liked. She was upset with me because of the suggestions I had given her. I have not spoken with her since. She sends me an email a day later saying that she final checked a vendor that I had given her when this whole thing started, and they indeed had the envelope she was looking for… she's out of control! Please help!! Do I tell her how she's lost her mind or ignore it, and become all of a sudden.. "unavailable"?