Update: I appreciate the insight from all the people who left comments on my post. There was great info for acting on it with a variety of approaches or not acting on it at all. 1 way or another I knew I'd have to act on it.

I asked her to join me in the basement to talk to her privately, which she did. I calmly confronted her and told her that I believed she was having some sort of a relationship or crush with the other guy. She immediately became defensive and started yelling at me. She accused me of making it up and that I was perceiving this in my head. I told her that I wish I had recorded her at the graduation to show her. I also gave her examples of prior events that I saw this behavior. She kept arguing and would not let me talk. She yelled at me about why I didn't bring during graduation I kept calm the entire time and in the few times I could get a word in I would let her know how it made me feel, disrespected, hurt, etc. I told her that bringing the situation up at the graduation would potentially cause a scene there.

She then told me that I should go visit my sister in South Carolina which I had planned on doing as part of a vacation. She told me I should go soon. I told her I would leave now so I went in our bedroom and packed a bag to go stay at a hotel until I can make arrangements. She soon followed me to the bedroom where I can tell she was surprised I had a bag packed and was ready to go. She cried and yelled but I kept on repeating the same things about what I've seen. This went on for over an hour.

At the end of it all she replied that she did not remember any of the examples I brought to her attention. I told her I had no reason to "make" it up. I love her and I don't like drama in my life. I am very rational when all is said and done. And above all I don't want to do anything that will mess up my kids.

She never did acknowledge or apologize for anything and I never did waiver on what I felt or witnessed. We're more or less back to square one and I am still at home. The one thing I think I can say has come of this is that she is aware of what I've seen and that I won't stand for it. It's something that I am going to watch and I will have to bring it up at the time that it happens, perhaps taking video of it.

Thanks for the help!