Hi Kseniya, OED is right in that normally you would use Ashamed of (I'm ashamed of myself for doing _____. I'm ashamed of him for doing _______ ) Ashamed at is quite specific. The most common use would be to talk about an event in the past that is related to you, "I was so ashamed at that meeting" Finally Ashamed about would be talking the specific circumstance - it sounds more direct. I'm ashamed about the way I ruined the child's birthday party. So in short - Of - General usage At - specific event/location looking back About - specific event with reason. Mostly though, ashamed of the conversational norm. Hope you're having a great day. Brad

‘To be ashamed of something’ and ‘to be ashamed about something’ are sometimes. interchangeable except that you would never hear ‘ashamed about a person’. ‘Ashamed of’ is perhaps stronger and more personal , you can be ‘ashamed of someone’ and ‘ashamed of yourself’.

‘Ashamed at’ doesnt really exist however

почему то я думаю что на русском хотя не правильно может и понятно, что-ж это тира я стесняюсь из/от/с , я стесняюсь на, я стесняюсь о/про, на англиском это работает потому что все подразумевают причина, но конечно это зависит и иногда звучит естественно в зависимости от того, что ты говоришь