What is the meaning of "that broke meter" in this context? Does it have a meaning like way too much or out of control?
Yes. By the time I came to Life Studies I’d been writing my autobiography and also writing poems that broke meter. I’d been doing a lot of reading aloud. I went on a trip to the West Coast and read at least once a day and sometimes twice for fourteen days, and more and more I found that I was simplifying my poems. If I had a Latin quotation I’d translate it into English. If adding a couple of syllables in a line made it clearer I’d add them, and I’d make little changes just impromptu as I read. That seemed to improve the reading.