welcome to HCM!
I have read your question carefully & I can understand your pain.
From all data provided, it is evident that your boyfriend has some psychotic illness, may be due to excessive use of drugs.
needs more detail information from patients or attendant. like if he mutters / smiles to self, etc. Schizophrenia is also a type of psychosis
you have not mentioned about treatment , so I assume he is not taking any medicine regularly for any problem.
There is mentioning of suspiciousness, sudden unprovoked anger outbursts, along with short attention span-- reflect the deteriorating mental health. I have seen such cases showing good improvement with medicines. Stopping cannabis completely will also be very helpful for him. Cannabis is notorious to cause variety of psychiatric disorders.
If it is possible, take him to a psychiatrist
, and start medicines, also get some basic tests done- lipid profile
You may also take help of some common friend and his family to persuade him initially , with time and with medicines his aggression, suspiciousness will go down and he will start accepting medicines wilfully.
There is provision of depot antispychotics for uncooperative patients in psychiatry. Here, an injection is given once a week to once in a month depending in his condition, and daily drugs are avoided.
Do not loose hope, such cases are well tretable.
Hope the reply helps you
Feel free to ask more queries related to this
Dr. Manisha Gopal