My ceiling fell on me? US-MD

Hi! I've recently been having difficulties with a landlord in Baltimore county. Extremely sorry for how long-winded this is. We already want to contact an attorney (recommendations appreciated as well!). But I wanted to see if any of this is worth pursuing, or if I'm completely out of line here. I just need a reality check.

The apartment itself was/is illegal. It's the 1.5 br attic above their portion of the house. (House was built in 1953, and they have owned it approximately 3-4 years before renting it out, allegedly.) It is not listed as mixed use, but only residential (not sure if this matters in the state of Maryland).

I was living with my fiance and a third roommate. We had two cats. The landlord is trying to charge us $300 (or rather: keeping $300 of our $1000 security deposit.) to have the carpets professionally cleaned because "how can [he] know if they didn't pee everywhere". This man has never owned cats and did not believe me when I told him he would smell it if that were the case. My cat is geriatric, and both cats were kept in our individual rooms for most of the day. It frustrates me that he wants to keep $300 for suspected damage from cat pee that doesn't exist, when to my understanding, pet hair and basic professional cleaning (NOT including cat pee) would fall under basic wear and tear. I was under the impression that landlords in Maryland cannot charge for basic wear and tear cleaning. I can't find a clear answer about this one way or another.

The next major issue: in the ceilings for the bedrooms, there are cardboard tiles installed--ones from around 2002 (made in 2002 at least) that are meant to be put up with staples. (Which I don't believe they were based on how they looked after they fell--at least not all of them were stapled!) Our bedrooms each had a pet water fountain in them, nothing crazy. They each circulate ~2.5 L of water. Usually less, since we are lazy, and they were often not completely filled. During our tenancy, the ceiling tiles fell out of the ceiling. Some over my computer, and some over my bed. I woke up to these tiles, dirt, dust, and insulation falling on my head. Tiles fell out of the other bedroom's ceiling as well. All had begun to bow before they fell, but it happened so gradually that it wasn't noticeable until, well. they fell. Landlord claims this is due to the pet water fountains causing high humidity. When I questioned why the insulation was black and dusty, He said it was dirt and sand (I dont NOT believe him, but it felt alarming).

Our angled walls in our rooms (so where the roof would be) were consistently warm/hot during the summer. The walls in our roommate's bedroom also began sweating off the varnish(?) which again, we don't feel was our fault, because the walls were hot from the sun beating down on the roof. We can't comprehend how 2.5 L of water would cause that much humidity. It was made worse when we didn't use air conditioning; our floor easily cleared 80°+ without it, despite their home having central air. (one vent per bedroom, no vents in the living room, and a vent in the bathroom. only push-vents, not pull-vents to pull air out.) There was about 3 feet of radiator in the living room for winters.

The landlord has admitted that the previous owner had the roof replaced because of water leaks.

Our argument: Summer 2024 was the most humid summer, if not second to 2020s summer, and since we are in an older attic with no ventilation*, the humidity seemed to be beyond our control, and we feel that the tiles would have fallen regardless of who used the space. We should be able to keep our room doors closed without causing danger to the property, right? I've never had this issue anywhere else I've lived. even at my own house that has these same tiles in the ceiling. It felt insane for us to be blamed for this, due to less than 2.5 L of water circulating in a container, but. yeah. After the tiles fell, Landlord came up and put screws and washers into them to keep them held up.

*(no over-stove ventilation, no attic fans, one window in each room but all occupied by a fan or AC. our one vacant, usable window was in the living room.)

For the ceiling, they claim they got a quote of $1,590 to replace it from the damages, to put in the same type of tiles. They sent this quote before having a real inspection done; all they had was a man come up to look at the ceiling while we were home. He did not remove any tiles or physically assess anything. He was there for all of 20 minutes. I attached their email showing their price breakdown. TLDR; they want to keep all but $200 of the entire deposit for all of this.

Worth mentioning per Maryland law: we were Not given any written notice of our rights as tenants when I paid the security deposit in 2023. Our rights were not in their lease they wrote, either. I know that when this happens, landlords are not entitled to keep ANY of the deposit. It's a husband and wife renting out the upstairs portion of their home, and not a company, if that makes any difference.

(a few days ago) I asked to see the Certificate of Occupancy and proof the space was inspected, he looked confused, and said he didn't understand. This was after claiming the apartment was legal. After a long discussion, they came to the conclusion that we may get up to $200 back from the deposit.

Am I insane? Am I in the wrong? Help :(