Is He Right

I usually don't trust guys when they give advice on the female body, so his he right? No judgment just curious

This was the first time me and my boyfriend had sex and I told him it was okay for him to cum in me. He did and I went to the bathroom and started douching. He came in and asked why I was doing that. I told him to wash out the sperm. He said that doesn't get rid if sperm. I said yes it does. He said no it doesn't. And we got into a fight about it. He gave up and said fine. Have fun fucking up you ph balance and getting a yeast infection. I told him they don't do that. He said yes they do and I'm not fighting over this. That was it. Is he right or was I right to not listen?

Edit: So after everything you guys said and doing a bit of research I was going to go apologize and I realized he left. He came back with a Walgreens bag that has Plan B in it. I apologized and he said it's cool. I definitely want to educate myself more because I feel so dumb