Grieving my ex?

My first love died 13 years ago.
His birthday passed 2 days ago & I can’t get him out of my head.
I’m currently happily married with 2 kids, but I always regret my choices that I ended our relationship.
He was a walking green flag, but I was young & immature.
He had healthy platonic friendships with other women, & they never had any bad intentions with him. & I’m sure if that changed, he would have stayed faithful. But we never got to find that out. I made more guy friends out of spite, & as you can imagine, those guy friends. ALL. had bad intentions & horrible influence on me. I let them in, so I essentially allowed them to poison my brain. Especially the tall, dark, & handsome one. He promised me he wouldn’t have any other girls in his life that weren’t his family if I was his girl.
My 1st love & I were growing apart once I let this happen. We were inseparable for almost 2 years until I found out just how many female friendships he had.
So I asked him one morning after we hadn’t talked over a weekend for the first time, “Do you even want to be with me anymore?” (Dramatic, I know. I was horrible on so many levels…) & he responded with, “I don’t know…”
So.
I let him go.
I got with the tall, dark, handsome guy. He was nice to me in the 1st year, but then my ex died & everything changed.

My 1st love was in a new relationship, & she cheated on him. Soon after, my ex got into a freak accident & died.
I don’t want to say it’s suicide, because he very well could have just been distracted… but. Life is so fragile…

Obviously, the next relationship didn’t work out. But. I never fully grieved my 1st love. The new guy was wildly offended when I even seemed upset. At one point, he told me that I should just join him. Still, I ended up being with him for almost 5 years.
But! After a year that I finally got away from that relationship, I met my now husband. We have been together almost 10 years & have 2 gorgeous children. We are so happy, but still.

On the anniversary of his death, or his birthday, or our anniversary… I always think of him. & some years it’s harder than others (like when I’m pregnant, but I haven’t been in 2 years) & this past week I’ve been so upset over it??
Nothing bad is happening in our lives besides the general stress of the world.
I’m just so upset for some reason?