Sounds like the owner is being unreasonable - Most landlords would kill for a good paying tenant for 5 years. Only thing you could have done more is to have the property professionally clean
Definitely making an offer before court will help.
As you said having copies of all communication will also greatly help. The courts are supportive towards tenants mostly
Unfortunately you signed the lease for 12 months - as disappointing as it is that you felt pressured to do this and with a family member sick won't matter to the courts so I wouldn't bring that up.
Good luck - would be interested to know what happens if you remember
