I get so much anxiety thinking about things that happened at the begining of my relationship

i could really use some advice , at the begining of me and my partners relationship she told some lies and done some silly things that gets me down when i thing about it , after 1 and a half month of dateing my partner she had liked a guys *** picture (who she has previous history with) , she tells me it was nothing but i cant help think that she wasnt that interested in me at the time and i was just an option or that something was still going on between them , it makes my anxiety spike and i feel sick to my stomach when i think about it it gets me really depressed were i shut down and overthink, can can anyone give me some advice please im really struggling , we both love eachother deeply and have a son together but i just cant seem to let go of some things as they still hurt when i think of it and its hard to stop these thoughts coming to my head