TIFU by making my buddy realize his daughter is probably not his.

Throaway, since my buddies gf knows my reddit. I don't even know how to start. But here it goes: me and my buddy are both in our mid 20s and work as engineers for the same company and we've know each other since high school and hes pretty much my best friend. We played a couple of rounds of cs tonight and were talking via discord. His gf works as a nurse at the night shifts sometimes, we usually use this time to game. The usual stuff. After the game we decided to take a quick break for a couple of minutes, so we did the usual shit chat. We somehow talked about school and how both of us really never enjoyed their time there as we grow up (we had both been bullied for being nerdish back in our school days). My buddy said that he hopes his daughter who is 3 f will have a much nicer time later in school/high school compared to him. It got to the point where we talked about all the "unimportant" stuff we had to learn while we were there. Well for me I've always disliked biology classes as I hated the teacher back then, I mean really hated them. And I said jokingly to my buddy trying to sound like my old teacher "the only things my 6th grade biology teacher taught us are "mitochondria are the power plants of the cell" and "you can tell if ya mama cheated by your eye color". My buddy laughing at this point "really the eye color?" and I said "yes, apparently." My buddy "how?". Me "take me for example, I have blue eyes and so does my sister. Apparently blue eyes are what call a recessive gene. If one parent has blue eyes and the other has brown there is only a small chance for your kid to be born with blue eyes. Well my parents both also have blue eyes of their own. So it would be more than unlikely for me to have brown eyes..." My buddy said " the more you know" than paused for a second. Than he said "be right back, gotta make surez the little one goes sleep now" after that he returned roughly a minute later and I could hear him almost sobbing "me and my gf also both have blue eyes... But my daughter doesn't". It took me sometime but I could calm him down eventually. So after that we both spent some time googling away but nope blue eyes are recessive as I remembered. We found out that if both parents have blue eyes the ratio is 99% blue eyes and 1 % brown or green, so highly unlikely. My buddy quickly disconnected from the call. I tried to text and call him. But he didn't answer until 30 mins later saying he will call me soon. I stayed up all night telling my gf to go to bed without me.The longer I waited I started fearing for the worst. I texted him again and again, he always answered he'll call me in a couple of minutes. At 5 am he finally called me back and said that his gf came home at 2:30 am and asked him what's wrong, he told her hes not filling well and will soon get back to bed. He waited until she was asleep to call me back. He told me he will take a paternity test behind her back to have something official to "slap" in her face. Then he started to cry and I drove to his place to pick him up and we went to a late night drive thru and greped something to eat. I've never seen my best friend like this and I feel like I'm the one responsible for crushing his world. He told that he wanted to propose to her on valentine's day. But that's off the table. I dropped him off two hours later at his place. He said he will call me tomorrow. Now I'm typing this out laying in my bed next to my gf who slept the whole time unable to sleep. I can't shake the feeling that I destroyed my buddies life.

TL;DR My buddy and I were talking about 6th grade biology and found out while talking about it that he and his gf both have blue eyes and his daughter has brown eyes. So he's likely not the father and I feel like I've destroyed his life by casual mentioning 6th grade biology.