what is the function of "口惜しゅうて" in below sentence?


I searched for the word "口惜しゅうて" on the internet but I found "口惜しい". I want to
know how "口惜しい" changes to "口惜しゅうて" in the below sentence: "おぬしの生きざま,
**口惜しゅうて** 仕方ないわ!"




This is covered in the [Wikipedia
article](https://ja.wikipedia.org/wiki/%E9%9F%B3%E4%BE%BF#%E5%BD%A2%E5%AE%B9%E8%A9%9E%E3%81%AE%E9%80%A3%E7%94%A8%E5%BD%A2)
on 音便{おんびん} (euphonic change). This is a historical sound change which is
simply equivalent to what would be spelled 口惜{くや}しくて.




This is covered in the [Wikipedia
article](https://ja.wikipedia.org/wiki/%E9%9F%B3%E4%BE%BF#%E5%BD%A2%E5%AE%B9%E8%A9%9E%E3%81%AE%E9%80%A3%E7%94%A8%E5%BD%A2)
on 音便{おんびん} (euphonic change). This is a historical sound change which is
simply equivalent to what would be spelled 口惜{くや}しくて.

