<human>: Can you provide a brief overview of the text?

The day before new years Eve she tells me that her ex boyfriend just got back from over seas after a year. She thought that he wouldn't be coming back and now she's confused... We've been together for ten months and she's honestly the person I want to spend the rest of my life with. I've been in a three year relationship but this one seems more real. We talk about moving in together sometime soon and joke about what our babies would look like. Typical stuff I guess.  Then all of a sudden this guy messages her that he's back and now 'everything's changed'.

  I feel like I was just a replacement to make her feel better because honestly, we look a lot alike. Except he goes to the gym more. Everything fucking sucks and I don't know what to do. My ex girlfriend (3yrs) kept trying to contact me at various times in our relationship and I always told showed her the messages, never bid anything. 

She asks me to deal with it so I did. I told her I never wanted to see her again. Telling someone who has been with you for that long in your life takes a chunk out of who you are. But I did it for her. And now this situation. New years Eve I'm having a party at my place and I'm stuck in my bedroom with her all night trying to calm her down because she's sorry she hurt me. 

She just told me that she going to deactivate all of her social media because she keeps stalking him. Every day. I knew it was bad but not this bad. I just need some guidance, please help me.
<bot>: her ex boyfriend is back from over seas, what I thought was long term love now feels like doormat rebound. She still loves her ex, I never would have started a relationship with her if I knew that.