Me (24M) and my gf(24f) have been together for 3 years. During our relationship we had been through some problems. At the start of our relationship I had a female friend (22) and introduced her to my gf. She talked to her normally but she said there is something wrong with her and she doesn’t like her attitude towards our relationship. After a while i ended my friendship with her for my gf. Then told her about we had a friend group (3 man) and this girl and we all casually flirted her. And once she had feelings for me and once i had feelings for her but we stayed friends. My gf freaked out. I apologized. Then after a year to my Facebook some weird account sent me a pick-up line text. I didn’t even have profile pic. I wondered if it is some game and told my gf about it. I replied to asking who she is. She turned out to be a highschool student saw me in an event of my uni. After finding out who she was i blocked her and deleted messages. My gf asked for messages i told her Facebook deletes messages when you block someone because if i told her i deleted before showing her she would freak out again. And she was already mad because i didn’t tell a highschool kid that i had a gf because i didn’t want to share my private life with someone i don’t know. Later she found out Facebook doesn’t delete messages when you block and she got very mad at me. We fought over it and then made up. Few weeks ago when she was complaining about how i used to always bring my ex to make her jealous and maybe i would have go back to her if she ever texted. I got mad and told her to prove i wouldn’t go back to her that she texted when we were together for 4 months. Asking can we be friends on Instagram and i blocked her. She said she doesn’t believe me and she will text my ex. I had to admit that i said yes we can be friends and my ex called me on insta. We casually talked and i even mentioned i have gf. Then my ex wanted to see me and we had a brief video call. She apologised for leaving me without any explanation. I forgave her. And then the next day my ex texted again and talked about random shit. I felt very guilty and blocked her. I thought as long as i am not flirting with her that wasn’t cheating. And i couldn’t tell my gf because she would lose it. And she did. She texted my ex. My ex veried texts or calls weren’t flirty and brief. She says “no one else but you does just messed up things”. I am telling her i was immature but i learnt. I never loved anyone else besides her. And I want to be with her. She calls me a cheater. She told me “write about this to any site and see if people are thinking your intentions are pure and immature only or messed up and something is wrong with you”. I do truly love her and repent. I didn’t do such mistakes again but she doesn’t believe me. I am serious with her and she is the only woman i introduced to my parents. I did some mistakes i am embarrassed of out of my immaturity and curiosity but I never had any feelings for anyone but her. How can i prove my innocence? How can I win her back? How can I restore her trust? I wanna marry her. I don’t want to lose her.