He should not have claimed you as a dependent since you had gross income of $4,150 or more. Plus you must have lived in his household for the entire year and he must have provided over one-half of your support since you are not related to each other.
If you had taxes withheld from your wages reported on a W-2 then you should file a tax return go get the taxes withheld refunded to you. You would file as Single and Not a dependent. Or if the income was from self-employment and you were either paid in cash or received a Form 1099-MISC, then you are required to file a tax return to report the self-employment income.
The following are the rules for claiming someone as a dependent under the Qualifying Relative rules.
To be a Qualifying Relative -
1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross income for the year must be less than $4,150 (social security does not count) in 2018
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.
