Bed Bug

It has been over 7 months that I moved into this Apartment. Recently, I found Bed Bugs.

When reported, the apt management says I have to pay for pest control treatment since it came from my old mattress. They showed some black spots on the Mattress to prove that this is the proof that Bed Bugs existed in this Mattress before

It is true that I purchased a used Mattress (private Party) but that was over 7 months back when I moved into the apt. And there have not been any manifestation of bed bugs up until now.

There are other apartments in the building which has Bed Bugs and there is every possibility that my apartment (as well as Mattress) got infested by bugs from other apartment

The lease contract does not say anything about this and Mass law says that Apt Owner is responsible for pest control.

Q1. Do I need to pay or am I being ripped

Q2. I will be moving out in another 4 months or so, is it wise to pay now and then sue after I move out (and recover my security).

Thanks in advance

You have to pay if you caused it. But if not, take them to small claims.