No, this is not AT ALL realistic. You would not be able to defecate without expelling the condom. I don't know what articles you read, but there is a LOT of unreliable information on the internet. It really isn't possible for any object to be stuck in your anus for more than a day or two.
Anxiety can cause abdominal and stomach pain, but so can a lot of other things. You should see a doctor to help diagnose what is happening, but I can say with CERTAINTY that it has nothing to do with a condom, or anything else, stuck in your anus.
I see you continue to ask when you are being told that this isn't going to happen. Three of us have never heard of something being stuck in an anus for two years. It just doesn't happen. I'm wondering if you develop this kind of anxiety level easily and it wouldn't be a good idea to talk to your doctor about that.
Years and years ago, I lost a condom inside my vagina for about a day, maybe a day and a half. My body pushed it out as I was walking. It would be the same if it came off in your anus.
As Curfew says, lots and lots of things can cause abdominal pain, but it's not a condom after all this time.