I am unfortunately not expert at paternity as revealed by blood types. The kind of writing on the topic that I've seen says things like, "in most cases," an AB parent and an O parent will only have A or B kids. There are a few possible ways this is not true, except they are very rare. Here's a link to an article that explains the exceptions:
https://www.thetech.org/ask-a-geneticist/ask427
It would be simpler to do DNA tests than to try to puzzle it out from blood types, at this point. Just in case of that rare chance that you are a chimera, possibly yours should be done with a both a cheek swab and a blood draw.
Do you intend to stay married and to be an equally good dad to both kids, or does splitting up with your wife ride on this? It sounds like in any case you should do the DNA tests, since if you are going to wonder and be stressed over it anyway, you should have the correct answer, on the slim chance that you're a rarity.