i stressed on everything must be able to work offline that in case even if i am already hacked, i am not in danger of losing anything except the coins i want to spend which will always be on the machine whatever it's online or offline.
What machine are you referring to? The host? As I wrote earlier, if your host gets hacked then your VMs you should be also considered as compromised. Ideally, it would be great if you used a completely separate machine to sign the transactions. Creating raw transactions using Bitcoin Core is a bit complicated so I would recommend you either using Armory + Bitcoin Core or Electrum (backup would be in a form of 12 words which you wouldn't need to update unlike Bitcoin Core wallet files).