My cat is missing.

I don't know how to start this post. My cat sometimes wanted to get out and I don't know why. Like whenever I was leaving the house he would sometimes try to sneak out with me. He fell down the balcony once. It was a year ago. Now he's gone again. He didn't sneak out cause I didn't leave the house today. No balcony was open. Last time I saw him was an hour ago or two. He was sleeping on top of my bathroom cabinet which he always does. And there's a small window thingy on the very top of the wall. It's slightly open and my cat goes out to watch the scenery there. It happened hundreds of times. I feel so guilty. I knew I shouldn't have trusted but I did. Nothing happened so I thought he'd just keep on sleeping. I check on him regularly cause I miss him. I check again and he's gone. I checked everywhere. I've been searching outside for an hour. There are tall grasses that surround my house that no one takes care of. I checked everywhere. I checked where he last hid and waited for me the last time he fell down

Just hours ago he was sleeping on my lap. And I was looking at his pictures. While he was sleeping on my lap. I wasn't ready at all for anything like this. I didn't think this would happen. I hate myself and I am aware I was so irresponsible and I hate myself for it. He's gone and I cannot find him. I don't know what to do and I don't know what to do without him.