Thread of the oil drain screw broken – repair???

Thread of the oil tank broken – repair??? Hi together. I have the following dilemma: On Saturday I wanted to make an oil change on my mopped. Oil, filter and copper ring were available. Gun attached to the drain screw, rotated, rotated and turned. Unfortunately to the right. (Trottel, I know) Ging also relatively easy, hardly resistance. After it occurred to me that I hit the wrong direction, it was already too late… Thread of the oil tank killed. Nu In the meantime I have expanded the oil pan to repair…. I would need a good tip. – Larger thread in, larger drain screw ? – Helicoil repair in the workshop ? – Another better idea ? Who of you has had a similar problem and presents me his solution ? Waiting for your advice …. LG Michael