Getting contacts from Microsoft Exchange on my iPhone
Although your phone and your exchange are now in sync, you did not merge both databases. 
By 'deleting' you relpaced your phones contacts with those of the Google Exchange Server. 

Your contacts are backed up inside the general backup of your phone and if you restore your iPhone from those backups you get your contacts back, though loosing everything new since then. You can extract the contacts directly from the backup with tools like iPhone BackupExtractor. You should be able to import those directly via the gmail webinterface.