It's common to want to talk about others every once in awhile but if someone does it constantly? That person is a toxic person and it's best not to have them in your life. They're probably talking about you behind your back just as frequently.
It's probably not a good idea to have someone in your life that snaps at the smallest thing. You don't know what sets them off and you'll probably always feel like you're walking on eggshells around them.
These types of people usually have to make everything about them. It's fine to have a little pity party every now and then but it's unhealthy to do it constantly. It seems as though nothing is happening in their life without them being a victim.
It seems like the only thing this person can talk about is themselves. You can't bring up any topic without them always redirecting the conversation back to them.
This person is one of the most toxic people you could meet. They manipulate the conversation and your feelings to their own wants and demands. It's best to avoid these people whenever you have the chance.