bash - Parsing a comma-separated "key: value" string -

i have text file several blocks several lines may this:

{ key1: value, key2: value,   key3: value,   key4: value, key5: value }  { key1: value, key2: value, key3: value,   key4: value, key5: value } 

given key, how can corresponding values? note neither key names nor values have fixed length, blocks start , finish braces , pairs separated commas.

my first try grep , cut, couldn't keys. guess should easy sed or awk, syntax confuses me lot.

first solution grep:

grep -o 'key5: [^, }]*' file 

shows someting like:

key5: value key5: value 

to remove keys:

grep -o 'key5: [^, }]*' file | sed 's/^.*: //'  value value