AITAH For checking up/ snooping on my fiancé ex

We have been together for 4 years m22 f23 and ex 21 They dated for two years 6 years ago as children and every now and then she will text him from fake numbers saying “i miss you or I was thinking about you” “remember when we did this or I am still in love with you “and he has always shown me the text and blocks her but a year ago I kinda started to get obsessed with hating her I hate everything about her and when she has the chance to text me she makes it very known she hates me back by calling me insults and other things. My issue is that I started a fake page and now I keep checking in to see if she’s posted anything if she looks better than me if she’s doing better than me and sometimes I get bad anxiety cause I want to stop looking and I just get this itch that I have to scratch. I just need help if anyone feel as such or has dealt with anything like it. I understand how unhinged this is and I also have hobbies that keep me occupied I have a great relationship with him but it just this thing.