Absolutely, we deserve to know everything that's happened in our marriages. I asked about earlier affairs, ONS's, whether all four children were mine, you name it. My wife's answers, and the way she answered, convinced me that I was dealing with just one affair (LTA, though). It's important to know whether you are dealing with a fallen women who went off the rails one time, or a serial cheater who cannot or will not control her behavior without intensive IC.
Knowledge is power.
Sorry you find yourself in this situation, hang in there.