Product: Debt collection

Good afternoon, I am writing to you guys regarding a collection I have pending from the company Columbia Debt Recovery LLC, dba XXXX XXXX XXXX XXXX XXXXXXXX XXXX XXXXXXXX XXXXThey sent me an email on the date XX/XX/XXXX. I would like to dispute this collection. Reason being, is because I used to be on a lease with my ex partner that we both singed, he was the primary resident and I was the co- applicant at XXXX XXXX XXXX XXXX XXXX 
We started the lease with The Cottages in the date of XX/XX/XXXX. On the year of XXXX I was pregnant with twins and I wasnt able to work since it was a high risk XXXX. My ex partner took charge of all finances, thats the reason why we approved in the first place at the XXXX XXXX  and I had signed because I was his partner and I was going to be living with him, as what I was told there by the leasing agent. Long story short about my ex partner since it has to do a lot with this situation of the collection agency charging me. 
My ex was very abusive with me and when I gave birth to our twin boys on XX/XX/XXXX, XXXX weeks after birth he had strangled me and I had contacted law enforcement on him. Point is he had a restraining order and well he didnt have where to go, I decided to grab my things and leave to my mothers with my children I have XXXX since I also have a XXXX XXXX XXXX daughter. I stopped living with my ex partner starting the dates of XX/XX/XXXX. He then decided he wanted to break the lease with them. He went to go end the lease with the XXXX XXXX on XX/XX/XXXX. But they didnt notify me to go sign the lease to end the day my ex partner went to go sign off on it. Since on their leasing agreement they have on the XXXX that any changes or termination or circumstances would have to be signed off by the renter or renters if there is more then one. They didnt contact me until almost the end of the month on XXXX XXXX and they sent me a email at the end of the month stating that they were trying to contact me and I have not responded to them which was a lie because they didnt try to call me at all and the only time they called me was to charge me a fee but never to sign any papers to end the lease. 
My ex partner then after a few months reached out and told me he ended the lease and that he paid all the fees he was supposed to on that day he ended the lease on XX/XX/XXXX. 
The only reason the XXXX Cottages called me was to charge me the amount they were asking me for when they even had made it clear that my ex partner already paid for and they want to charge me too because I didnt end the contract with them but then again they never called me to go in and sign papers they just kept charging me and what I understood was that my ex partner had already paid all the fees and theyre making me pay as well a double fee. When they called I had also asked them to send me over documentation to sign off so that we can end the contract since they just went ahead and made the termination that day with my name printed on there and just my ex partners signature. 
I am currently not working Im actually in horrible debt at the moment my twin boys are barely XXXX XXXX XXXX and I have a XXXX XXXX XXXX daughter. They kidnapped my babies last year and I paid so much for a good lawyer and all the courts to get them back. Ever since Ive been trying to get back up on my feet and its truly very difficult for me to pay that amount. 
I am in debt with my lawyers and I have many many court fees and personal debts. I hope you guys understand my matter. 
Well Now I have the Collections Company XXXX Contacting me through email and also through my phone. I responded to their email right away by sending over a request to dispute my collection and I had also sent them the reason for the charges, and that I would not be able to pay them for that because it was all a misunderstanding on the date of XX/XX/XXXX. 
Surely after XXXX week they started to blow my phone up and started to charge me and started harassing me. They even called when I was at the airport trying to help my mother travel and asked them to please not call me and that I would be hanging up on them now, the lady started to raise her voice at me telling me that I need to pay it that when was I going to be able to pay it and she didnt let me speak at all because she was speaking over me and I hung up the call. 
Today XX/XX/XXXX I got a call and it was again to charge me on the collection. I asked if they received my letter on wanting to dispute the charges and yet she still insisted that I have to pay. I even explained to her again everything and yet she got angry at me and told me to get assistance and when I do to pay the fees because regardless it wasnt going to wait on me and it was going to affect me dearly. It sounded more like a threat to me. 
So Im reaching to see if you guys would be able to Dispute these charges and understand that it was all a misunderstanding and that I have been getting harassed by this collections company even after responding to them they still contacted me even though their email said they wouldnt try to reach out after hearing from me. 
Down below I will attach all documentation I have about this matter. 
I appreciate you guys for your time and I hope you can help me dispute this issue. 
Thank you,