It's been a month and a half since he broke up with me. Today, we happened to walk right past each other. I don't think he noticed me. The moment I saw him, I started to tear so I walked away as fast as I could. I thought I was stronger than that.

Is that a normal reaction to seeing an ex? Or should I go through some counceling to get over him?

Give yourself more time, and if you stay busy and learn to be happy with yourself, you can better handle the surprise in seeing an ex. If it persist to long then help is a good idea.

I'm 6 months into my breakup, and that is the one thing that scares me. Seeing my ex with new guy.

It has only been a month and 1/2 so it is still normal to be upset. Healing a broken heart takes time and for everyone it is different. Go out with friends and involve yourself in other activities.