I'm looking for advice. not shame. Update!

Zerenity • Arizonan.• Living life to the fullest.•Nature addict. ❤️ Sister to a Marine 🇺🇸
I've contacted the credit company in regards to the debt and it is infact mine and they've negotiated with me a settlement instead of the whole amount. However it will not take it off my credit, yet they will show proof I'm no longer liable for the remaining amount. The remaining amount is now being held accountable to my ex and he can handle that. Definitely a lesson learned. Thanks to the ladies that offered advice! 
Recently, I decided to leave my ex of 10 months. We fought after the 5th of month of dating, and then I was cheated on. It was a long distance relationship to begin with and we tried to make it work. This is where it's biting me in the ass... it's a long story, but please don't just glance without commenting. 
everything was going great. In May his lease was up, and though just started a new job, he wanted to find another apartment to live in. He finds one, and lets me know about it, but he needed my help. That help meant by pretty much my information. Name, DOB, etc etc and pay stubs. We go into the office and explain our situation to the lady. My ex had a prior eviction from North Carolina and they said they would accept it if it was over 6 months old. Which it was. Well, we both discussed also with the landlord that I had thought about moving but with my current lease being in effect, the landlord was very hesitant in even letting me sign since technically I wouldn't have been living there. 
Here's where it gets picky. 
My ex NEVER gave me proof of the lease and said I had no rights to a copy.A couple   months went on and (these were hotels before, so it's that layout) and two bodies were found dead in a complex across the way: (he was on the second floor), then also, literally right outside the parking lot a shooting occurred and someone was killed. That's 3 murders in a 2 month time span. My ex then decided to abandon the apartment and move into another one. Let's speed forward to now. We're split apart. I decided to not move in with him after everything we planned. It didn't feel right. On Friday I went and got my belongings from him and returned home. Today, on my credit report I get an alert for the apartment complex charging me $1,781!!! I never lived there! I didn't get a copy of the lease, and I wasn't told about the abandonment till last month! This makes it 3x harder to get a place anywhere because of the apartment complex listed!! Should I dispute this? I have (well technically) now expired lease showing I lived through my entire lease and the reason I couldn't move was for medical issues. I also have stayed with my current job I have been with for two years. I feel like this shouldn't be my financial responsibility! Even if I pay my part, will it be taken off my credit? I'm so furious over the whole situation. I texted my ex and he then said we'll you were expecting it to happen, so you can take care of that too. Mind you he got my car impounded that he agreed to take over for the title and so on, but left it abandoned somewhere and I just got that letter this month, and it was surrendered/taken care of! He was using my information for his car insurance, I canceled that too. I've spent so much money taping his damn holes that I'm in a MUCH BIGGER hole now with this debt. Anything helps. I'm just angry and lost and a bit pissed off that someone had to be this shady and stab me in the back. If you've been through something like this, please give your experience. I hate to turn to a form like this, but it's the only way I could get advice. Thank you ladies.