How many domestic violence cases were brought in the ward that uses "ward13@cityofchicago.org"?
domestic violence refers to domestic = 'TRUE'; uses "ward13@cityofchicago.org" refers to ward_email = 'ward13@cityofchicago.org'
SELECT SUM(CASE WHEN T2.domestic = 'TRUE' THEN 1 ELSE 0 END) FROM Ward AS T1 INNER JOIN Crime AS T2 ON T2.ward_no = T1.ward_no WHERE T1.ward_email = 'ward13@cityofchicago.org'