Test positive today (!!) but did MDMA last weekend

I'm so scared - did I damage my baby??? Didn't know I was pregnant because I got a big negative on the p-test last Friday, and then did a low dose of MDMA (80mg) last weekend, didn't get my period on Mon and now Today Friday got the positive. 
I feel so helpless and ignorant not knowing what risk I've put on this little thing! Any insights???