CIVIL MARRIAGE VERSUS CHURCH MARRIAGE
Civil law and canon law are two separate legal orders. Therefore obtaining a civil divorce or separation has no effect on the church marriage. And conversely, the declaration of the nullity of the church marriage (erroneously referred to as "church divorce" or "annulment of marriage") does not result in a civil divorce or separation. However, a declaration of the nullity of the church marriage may help to prove a complete and irretrievable breakdown of the marriage.
For those interested, here is the text of the Code of Canon Law.