Did I do the right thing breaking up with my girlfriend or am I over reacting

Alright so I want to get an opinion from someone other then friends or family. Me and my girlfriend broke up last year and she started talking to this one guy, we eventually got back together and I said that's the one guy I want her to talk to anymore and she agreed. Last month I noticed she followed him on Instagram and when I confronted her she said she was showing a friend him and forgot to unfollow him and it was no big deal so I let it go. Last week I saw she added him on snapchat and I confronted her about it and she swore he only sent her one pic and that was it but she didn't reply and forgot to delete him and it was no big deal. I confronted her again about and she said "well he sent me two but I didn't want you to get mad". I broke up with her because I feel like shes lied about other stuff if she can lie about that. Did I do the right thing or am I over reacting

This much is. not enough to tell if she is actually lying or if she is true.
Though, I must say she is the kind of person who does not does things as told. Such people like to take control of their lives themselves and do as they want. She might not even realize it.
I was before this kind of person so I can tell.