Girlfriend broke up with me. Advice?

@Wafflekitti29

Hey there, hopefully you are doing well. There's a few things I would like to point out;

Hello, I'm just here to ask for some honest advice. My girlfriend and I have been dating for a little over three years and I was so happy, although we've had our ups and downs. (I read your response. I truly belive the downs never got fully resolved, so this impacted the relationship in many ways.) I also had a friend named Kassidy, that I made the mistake of venting to about everything. (Its okay to do this since this was your friend. Do you did this because maybe you didn't trust she would listen to how you feel?)Megan, my girlfriend, didn't like Kassidy because she thought that Kassidy had a crush on me (which she did). (I see she felt fearful of losing you here, which is why she reacted this way. One things she might fear is abandonment and theres a high chance she doesn't feel good enough about herself) She thought that Kassidy was trying to tear us apart. (I can see her fears were actually real and also from the past as well. She might be a person who expects the worst, and she may not have gotten the kind of reassurance she needed that everything was going to be okay) And so she never felt happy with Kassidy around. Anyways, Megan broke up with me four times, the fourth time being a few days ago. And I've noticed that we would argue about Kassidy every time before she broke up with me. (Your ex seemed to be getting scared of losing you, it made her lose emotional self control, and then she either tried to manipulate or control on an effort to reduce her anxiety. There's a chance she might have done this with someone else as well, but during this moment she was looking to feel safe and that she won't be abandoned) I decided it was the best to remove Kassidy from the photo, and I hope this gives Megan a bit of relief. One more thing you should know, I cheated on Megan, and I feel like shit for it. Every day I'll regret making that decision, and I hope that you all hate me as much as I hate myself because I deserve it. (I wouldn't hate you for it. I do feel that you had tons of unexpressed words and feelings towards the relationship, and her behavior actually pushed you away numerous times. You are owning up to what you did, however you got to understand that your gf also did things to damage the relationship) I've been in love with Megan for a long time, and she broke up with me because she loves me, just not 100%. What do you guys think? Do you think I have another shot at it if I prove to her that I can be trusted? (Trust is something that can be easily broken and hard to gain. The good thing is that you admited what you did and looking for to overcome this. It's going to take a long time to earn her trust back, its very important to work on communication (such as; listening, empathy and validate) and being able to not let things mount inside) I love her so much and I'm determined to change into the person I used to be. The person she fell in love with. I'm sickened with who I am now. Thank you.

At the time, my relationship with Megan wasn't going well because she'd get irritated with me easily (which is understandable because I made dumb decisions).(The way she gets irritated can easily push a person away and kill the safety in the relationship0 This guy and I started talking in a romantic kind of way (which disgusts me to this day), and I didn't plan on officially getting into a relationship with him until I broke up with Megan. But I didn't know what to do or who to choose. That shouldn't have been something I was questioning. I should've chose Megan no matter what. (There's a reason you began doing all of this. I do think that if things were going well then it wouldn't have reached this point. The relationship wasn't working way before this happened, they were a lot of things both sides did that pushed each other away) Kassidy, at the time, was supportive of my behavior, (Was your gf able to give you this?) but I'm not going to blame her for a decision I decided to make. This is all my fault and I take full responsibility for it. And I feel like a piece of shit for it. How do I express to her how sorry I am? I plan on talking to her about it today, but I've already talked to her about it a hundred times. I feel like we just need to have one good chat about it. (It's not a good idea to keep going after someone who keeps breaking up with you, at this time it seems she wants to be alone)