A cat that managed to get out will continue to do so again for a length of time afterwards. I've found that male cats are also far more vocal about it as you've experienced. They're inherently curious creatures.
It won't be easy trying to keep him in now especially if you leave windows open. I use something like
these so that I can keep windows open and still allow air to flow through.
I've talked before how two of mine are mother and son but never explained how. One of the windows in my house broke, never figured out how, and Mitsy escaped. She was gone for months and I would only catch her out of the corner of my eye some days when I was outside. Having been an indoor kitty her whole life she didn't really have the proper instincts to hunt so while she did well enough to survive somewhat, it would have ultimately killed her. One day after coming home from the store I thought I kept hearing something crying underneath my porch so I checked.. it was Mitsy. She was incredibly skinny and frightened but still let me crawl under and grab her.
She eventually put weight back on and not long after came the surprise of her giving birth to kittens. Two of which I gave away and Rocky was the one I kept due to his condition and the chance he wouldn't survive longer than a year.
But getting back to your little one, aggressive tendencies can continue for a couple months even after being neutered. Only roughly half of all cats neutered will have those tendencies stop immediately.
Also the hissing and aggression toward you is because he's hurt and scared after those fights but here's the thing, he's still coming home to you, right? That's because he feels safe and loved there. Pets stick with us through our worst and best times and theirs as well though showing or even internally holding animosity for your kitty will only cause him to second guess those feelings.
I understand being frustrated and tired but keep showing him love and attention. Again he's wanting out because he's curious, not because he wants to get away from you. Try your best to keep him inside and with time he'll stop trying to get out. It can take months. Francis knows what I'm talking about as I gave him advice with the one he rescued and took in.
