Crush (I am a recent widow)

I am a recent widow (several months post). I have developed feelings for a guy friend that are confusing. He used to flirt with me before my husband died. I took it as harmless, but I definitely felt like he was into me. We went to lunch a couple of times (as friends) and never crossed the line. I was flattered, but had no intention of being unfaithful. However, I was drawn to this guy and realized that hanging out with him was probably not a good idea and I started to have anxiety about it. Fast forward, many months later, my husband died unexpectedly and I went to dinner with this guy a couple of moths later. I still felt the same spark. I felt guilty about this, but really wanted to get to know him better, so we hung out a few more times. My feelings have grown stronger and stronger to the point that I let him know. Once I let him know about my crush, he has pulled back and suggested that we should get to know each other better and take things slow. We are both mature adults. I don't know what to think. I asked him why he had flirted with me when I was married and he said because "I was safe". What in the world does that mean? Help me to decipher this strange behavior. I have really fallen hard for this guy, but I am wondering if he is just playing games.