To put it as simply as possible, think of schizoaffective disorder as someone struggling with a depressive or bipolar episode (it could be either way) IN ADDITION to symptoms of schizophrenia (e.g., delusions, hallucinations, etc.).
I agree with EB's recommendation to visit your partner's treating provider with him and ask him re: your concerns.
Otherwise, the best predictor of future behavior is past behavior. If he's been violent w/ you and/or your children in the past, it's definitely possible that he could be violent again. Not everyone who is schizoaffective is also violent; but if they have been violent, they are more likely to repeat it. The nature of an individual's delusions, hallucinations, etc. (and how much these are under "control" ) can also contribute to this.
Furthermore, please keep in mind that meds are not magic pills. They can HELP. They are a TOOL for someone to help cope and to get them to a better quality of life, to help them function, etc. The best course of treatment is typically a combination of therapy and meds--and, even then, there are folks who stop taking their meds, don't take them consistently, etc. It can take time for some meds to ramp up in someone's system, so (again!) they're not magic pills. Someone doesn't wave a magic wand and go VOILA! All is better w/ the world. Those who think this way tend to be sorely disappointed and then become frustrated when they (or their loved ones) continue to experience difficulties.
PLEASE DO NOT base decisions on whether or not to stay w/ him upon a bunch of strangers on the 'net. Many people talk out of their ass, provide misinformation (not necessarily intentionally), or have their own distorted views of these things. You really should be asking your partner if it's okay to accompany him to his provider's office to ask these questions. Depending on the nature of your current relationship w/ your partner, you may want to ask him if he would be willing to sign a release of information form for his treating provider. This way, he is giving the office consent for them to exchange information w/ you without his presence (he can restrict/limit this as he chooses).
G'luck.