If I married an illegal immigrant and he got deported over 3 years ago am I still married to him?

If you and your spouse were properly married (barring any legal impediment to marry, such as being too closely related to each other, or married to another person at that same time, etc.), then you are still married. Deportation does not divorce you. To be legally married to another, then you will have to get divorced.

If you were lawfully wed, and have not been divorced through the courts, then yes, you are married to someone who no longer resides with you. Deportation does not equal divorce. You can seek a divorce, and since you are not likely to be able to serve him, unless you know how to reach him, then you obtain the court's permission to serve by publication.