Need Snapchat experts !

Hi guys

So my baby daddy is apparently and has been for years on and off Snapchat behind my back And he is that greasy guy talking to a bunch of girls and yup lots of naked pictures and pretending he doesn’t have me or a baby YES I know to leave. YES we deserve better. YES I am smarter then this !

What I need help with is how Snapchat works. I found the naked pics by pulling on the screen, and some conversation but there is a lot I couldn’t see after talking to some of the girls

How do I know if he is on it again ? Do I have to be friends with him on it ?

I am not a Snapchat user, it’s confusing, and I don’t like how sneaky this ap is.

So as we are separating currently still living together and yup I am also 14 weeks pregnant with our 2nd.........I want to be able to know when he is on again.......

Please help ? And thank you !