1)is pinworms infection spread via washing machines? 2)if i wash my underwear there and then sm will wash her clothes, will they get infected?

No: You have to ingest the eggs. The most common place to get the infection is either from daycare or from sleeping in same bed with someone that is infected. The worms lay the eggs around the anus while you sleep, hence the itching or scratching.

No: The eggs themselves would disperse & die in such environments. They contaminate your fingers when you handle the bed linen of an infected person where they were dispersed. It can also be passed from handling the dry underclothing of infected persons. If the contaminated fingers are not washed before you touch your face/mouth, the eggs can enter your mouth & establish an infection in your gut.