'extremely relieved' is correct and usable in written English.
You can use it when you want to express a feeling of relief, especially after experiencing a stressful or difficult situation. For example: After we finished our project, I was extremely relieved.
Obama says he is "extremely relieved".
Through the disappointment I was extremely relieved.
"His cerebral activity is intact and we are extremely relieved.
Detective Hamdy's lawyer, Philip Karasyk, said his client was "extremely relieved by today's decision".
Deputy English was extremely relieved the suspect had been caught, she said.
Yesterday he was said to be extremely relieved his ordeal was over.
"We are extremely gratified and relieved that the last chapter is going to start," said Ellen Yacknin, one of the inmates' lawyers, who is also associated with the Greater Upstate Law Project here.
The technique, which uses an optical illusion, has already proved extremely effective in relieving the pain that some amputees feel in their "phantom limbs".
Some women find acupuncture extremely effective in relieving nausea, so if all else fails and if you can stomach the thought of needles (which I have to say I find completely painless), it's worth a shot.
In addition to ensuring that medical needs are met, etiologic information can be extremely helpful in relieving guilt that parents may feel about having a child with hearing loss (e.g., a mother who may blame herself for the hearing loss due to an unrelated event during her pregnancy) and can allay worry about other complications that may appear in their child.
My first non-fiction book has managed to attract the attention of no fewer than 27 reviewers and most of that number have been, I'm relieved to say, extremely positive.
