I am sorry to hear about this worrying change in Tango and the destruction he caused. My name is Rebecca. I am a veterinarian and will do my best to help.
For such a sudden change in him, the first thing I would do if he were my dog is a thorough physical exam, and basic blood tests, trying to find out if there is a physical problem that has caused this change in him, such as hormonal imbalances, low blood sugar, liver disease, etc. Dog can have separation anxiety and be destructive when left alone, but it is unusual for it to suddenly appear in a dog his age that has never been anxious before. Some kind of imbalance or neurologic condition may be the cause, and starting with an exam and some blood tests is where I would start if he were my patient.
If blood tests are all normal, and no problems are found, then I would treat it as separation anxiety. This means combining anxiety medication with retraining him to be by himself.
The only other explanation I can think of is that something frightened him badly that first time he scratched up the windows, something he heard or saw outside that made him want to get outside in a hurry, and now he feels that anxiety when he is alone. Anti anxiety medication may help (fluoxetine, clomipramine), but he would need an exam and blood tests before starting on these medications.
Let me know what other questions I can answer.