Hey @reachout
I hear how incredibly heavy this is for you. Living with a partner who has paranoid schizophrenia is an immense challenge under any circumstances, but doing it for three years without knowing, and now doing it without a support system, is enough to leave anyone feeling exhausted and lost.
I have been with my current partner for over 2 years, and they have paranoid schizophrenia, and their medication has really helped them in their journey navigating it.
That being said, it is completely valid to feel frustrated. Compassion for him does not negate the reality of the toll this takes on you. The frustration that you feel is often a byproduct of expecting a logical response from a brain that is currently experiencing a different reality. I would recommend that when he is symptomatic, recognise that his actions are a reflection of his condition, not his feelings for you or your worth. You also cannot "reason" someone out of a delusion. You are his partner, not his doctor or his crisis team; accept your limits.
Since you don't really have support from friends or family, it is important to look toward professional and community resources. You shouldn't carry this alone. SANE does offer a lot of information and recommendations of support here .There is also more information from helpingminds and mental health first aid international which may be of use to you. Even reaching out on here is a wonderful start in building a community of support!
If you choose to stay and work through this, structure is your best friend. If he is not currently on a treatment plan (medication/therapy), this needs to be a non-negotiable boundary. Schizophrenia is a medical condition that requires medical management. I also recommend using the LEAP (Listen, Empathise, Agree, Partner) method. It's a communication tool designed for talking to people who lack insight into their mental health condition. Having a safety plan is also important. Know the signs of crisis. Keep the number for a local mobile crisis unit/service, or a mental health advocate, handy so you aren't the only one responding during an episode.
It is okay to ask yourself, "Is this a life I can sustain?" Compassion does not require self-sacrifice. If the environment becomes unsafe, or if he refuses to engage in treatment, you have the right to prioritise your own wellbeing.
You have been incredibly strong for three years. It's okay to be tired. It's okay to need help.