you sound like me. everyone in my family that knows me well enough will say that I'm a rock and that I don't really cry. oh sure, I'll get sad and depressed and not say a word to people, but not cry. I've only really cried because I was sad once. that one time was not so long ago, in fact, only two summers ago. it was the day before my b-day and my German Shepherd, whom we had taken to calling Max O Million, was lying on the floor, silent. I figured that I hadn't woken him up, so I decided to go on as if nothing happened. hours later and I was still the only one up and he hadn't moved, so I decided for him that it was time to eat. so I called his name, but he didn't move. I shook him, but he didn't move.
that's when it hit me. I cried out his name, but still he lay there. I broke down and hugged him and cried...for the first time in a very, very long time, I cried for something worth crying about.
so in response to your question, no. you can't be a monster just because you don't cry, even for those closest to you. for if that makes you a monster, then the world is full of monsters, me included.