My ex's new boyfriend is literally stalking me

Hey girls, I need to ask you something. My ex's current girlfriend checks out everything I post and then unfollows me, it's the same cycle every week. On top of that, I think she's messaging me from a fake account because I got a really weird comment on my profile the other day. What do you think I should do? Should I just block her without engaging, or should I ignore it? I'm not sure, to be honest.