My husband has become belligerent in the last month. I’m his primary caregiver here at home. Any suggestions?

I can relate. My 89 year old dad is becoming like this (has pancreatic cancer and possible dementia). It’s heartbreaking and very stressful, I cry a lot. I just spoke with a good friend of mine, who’s a nurse and she told me this 1) this can be normal, as your loved one is no longer the same person, their cognitive brain function may be affected 2) though it’s hard try very hard to not take their verbal abuse personally, they don’t mean it 3) ignore them and when they are belligerent walk away, distract, deflect the argument. Do your best to not engage in it, it takes two to argue so let them talk and walk away 3) if they show sign if confusion bring them to ER
most of all take care of yourself and know you are doing your best

This can mean a decline.
The belligerence, is it preceded by a task that he now finds frustrating or more difficult to do? If so this might be the way he can communicate his frustration.
It can be a sign of other medical conditions as well. A UTI is one of the easiest things to check for.
It can be that a small stroke has caused damage to a particular area of his brain.
This is something that you should contact his doctors office about.
If the belligerence becomes violent then you need to protect yourself first.
Leave the room. (If it is safe for him and for you to do so)
Call 911 if necessary. Tell the dispatcher the situation. Explain that the person has dementia and you need him to be transported to the hospital.
there are medications that can help with the anxiety,

Has he been checked for a UTI? Drastic mood changes, delirium, and even hallucinations can all be caused by an untreated UTI in the elderly. That’s the first thing I would rule out in a trip to his doctor. Regardless, the doctor should be made aware of this sudden change.

This could mean that he has taken another step down in his dementia journey. It does happen in some cases where the person with dementia gets meaner. It could be his response to knowing that he is progressing and that's the only way he knows how to express himself, so the important thing for you to remember is to stay calm, and try and be nice and sweet, as often people with dementia, tend to mirror our moods and attitudes. If we stay nice and friendly, they most likely will too. I of course had to learn that the hard way with my husband, and hard as it was sometimes, it made my life much easier if I didn't respond to his negativity, with my own negativity.
You may want to give that a try and see if that doesn't help. And if it doesn't as with most steps down in dementia, this too will pass, and you will be on to the next.
You also must start doing some fun things for yourself, and not just the essentials. If that means hiring some outside help, so you can get away for a few hours every week, then do it. You're worth it. That too will help with your attitude and give you more strength and patience for the journey, as it it not an easy one. God bless you.

More details would be helpful in giving you advice.