Am I overreacting about my dad going on a trip with his “friend”?

Backstory: we just lost my mom a year ago to a terrible battle of pancreatic cancer. It was awful to watch my mother suffer and for my dad to be out of his depth as he isn’t medical. This “friend” was a friend of my mother’s but only came into our lives right as my mom was diagnosed. As for the situation, I don’t like this woman for my dad but I respect that he is a grown adult and is able to get back out there. He’s still “young” at 62 and I truly understand wanting to get back out there. But he has continuously said “she’s just a friend” or “I’m not looking for anything serious” which is cool. Take your time my guy. He was planning on taking a trip to Key West. He said continuously that he was going alone and said that to me and our friends(we share a friend group through our social groups). Turns out he lied to me. He’s with this “friend”. While I don’t like her, I wouldn’t actually care that they were going. I am extraordinarily hurt that my own dad lied to me about going alone. We have always had a great relationship and I respect him enough to not lie to him. While I sort of understand why he felt the need to, I am hurt and upset that he still lied and he doesn’t feel an ounce of guilt. The truth matters to me greatly and it’s not a boundary I thought my own father would cross. So I’m coming here for some advice if I am truly overreacting here about being lied to or am I right to be hurt by this? PS I apologize for formatting, I’m on mobile