Shell remove string including newlines

I am currently working on a custom source patcher and I'm having troubles with replacing string by another, including newlines.

For instance, I want to remove this pattern :

\n/* @patch[...]*/

In order to get this... :

this.is = code ;
/* @patch beta
    blah blah
*/
if (!this.is) return 0 ;
/* @patch end */

... to this :

this.is = code ;
if (!this.is) return 0 ;

And not this :

this.is = code ;
<- newline
if (!this.is) return 0 ;
<- newline

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Using a shell script, I'm using sed command in order to do what I want :

sed -e "s|\/\* @patch.*\*\/||g" $file > $file"_2"

This works pretty well, but the newlines are still there.

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This way doesn't work as sed can't parse newlines :

sed -e "s|\n\/\* @patch.*\*\/||g" $file > $file"_2"

Neither this method work : How can I replace a newline (\n) using sed? , nor tr (second answer on the same thread).

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Would you have any solution to this ? Even heavy ones, performance is not important here.

P.S. : I am working on a web application, and in this case JavaScript files. Under Mac OS X Yosemite, but no matter what system I'm using, it seems to be a common issue for all bash users.

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I found out another solution using Node.js for those who have troubles with their Awk version :

node -e "console.log(process.argv[1].replace(/[\n\r]\/\* @patch([\s\S]*?)\*\//mg, ''))" "`cat $filepath`"