I am thinking you can stop them. You published your work online. it has a date. It will be before they started selling the work and they will have no contract or agreement with you to sell them. have hope.
https://www.teepublic.com/copyright-policy
There is artwork from other patriots there. You all might want to check out his site to make sure he isn't using your work to make money off of. It is WAY more than one shirt.
bs
you let people walk all over you, they will.
not all people are filled with love and kisses