How do you get a Bartholins cyst?

My partner cheated about 2 months ago but said they never had sex, he doesn’t have any symptoms of anything but I believe I have a Bartholins cyst. (He’s the only partner I’ve ever had)

can you get it on your own? Could I have gotten the sti from the other girl?

How are ways this cyst happens? I’ve never had anything like this before and I’m still young. Can I get rid of it on my own or do I need to go the obgyn?