Making friends after 40

So, I am just now realizing, at the age of 45, how much I really need friendship and community in my life. And how I don't have it. My one and only close friendship (if you aren't including family/spouse) ended in middle school. The gradual dissolution of that relationship was partially due to a normal change in interests. But, in retrospect, I realize more of it was due to me being a selfish jerk. After I realized that, instead of dealing with my guilt in a healthy way, I decided I was just not good at being a friend and Instead of putting anyone else through that, it was just better that I not have close friendships. I've had a lot of "casual" friends through the years, even groups of people that I used to hang out with regularly. I always felt like I was just hovering around the edges of the social groups though. I have always reasoned that I'm just naturally introverted, and that I don't "need" socializing outside of my immediate family. This is just a lie I've been telling myself for decades. While it can be argued that statistics can be skewed in a lot of ways, the stats I've seen on forming close friendships after a certain age aren't encouraging. I don't even know how to start. I imagine the suggestions will be similar to how to find romantic relationshipsq