do I tell her husband?!

Shianne
My husband has been very open about his CRAZY ex with me since the beginning. He has always told me whenever she tries to contact him and when she has said inappropriate things, he always has shown the messages to me before blocking her. He NEVER responds with anything other than maybe a "leave me alone," but the last few months he just hasn't said anything at all. That didn't even work. They dated when they were in high school and now she is 27, married to an unsuspecting man, and pregnant. She is seriously insane. He has blocked her on every form of social media and she makes new accounts to try to talk to him. She was blocked on his phone too, but apparently got a new number and saw this as an opportunity to contact him again today. Hubby has told her a million times to back off, but she tried again today. I figured it was her when he showed me the text. I called the number to see who answered and sure enough it was her! I asked to talk to her husband by name (yes, I know his name). She asked me who the f@&$ I was and when I told her that I am the wife of the man who has told her to get lost a million times, she hung up. 
This chick is relentless. I texted her from his phone prior to him blocking her AGAIN a little bit ago telling her to seriously get lost before I tell her husband about her shenanigans. However, she does this ALL the freaking time, and I'm starting to feel like her husband deserves to know. MY husband is loyal, but who knows who else she has tried this with and how far she has gone. Do I tell him? Or do I wait until she contacts my husband again?
It is seriously disruptive, annoying, and I am feeling guilty that he doesn't know she is being shady.