Used to be close to close to family

I used to be close to my aunt, we were born in the same year a month apart. We lived in different cities but would always see each other. I have cousins but she was the only one who would stick by me. Whenever we visited she was there. I would rope her into coming with me to my cousins house because they never spoke to me while I was there.
We were like sisters. We went through break ups together. We supported each other.
However a few years ago I was going through this hectic break up and just started college with a very demanding degree. I didn’t have the energy to reply to texts but I always did when I could. She understood.
Finally she got a boyfriend and completely stopped talking to me. She never replied to my messages or as I came to learn she ignores everyone’s message on my side of the family. I was like ok, maybe she just needs space with her bf, so I stopped talking too.
So pedal a few years later, we still don’t talk as much but I thought we were ok. She still ignored my messages but I just had a lot of work so I stopped noticing. Then she got engaged and my mom and I both sent her congratulation messages for her engagement to this guy. She didn’t even read those messages. We sent her birthday wishes and she ignored those too.
So I was just like ok I’m not gonna put in effort into someone who I know won’t do the same for me. I won’t chase. I realize there’s more I could have done but theres only so much a person can be expected to do.
When we were growing up there was this cousin I didn’t like (one of the cousins who used to ignore me when I visited) because this cousin was kinda…well a bit too much of an attention seeker. My aunty knew I didn’t like her. She even used to talk about her behind her back and make fun of her. Not gonna lie I used to do the same. Turns out now they’re best of friends. Always posing and hanging out together.
Just makes me feel sad because I know they’re gossiping about me and I know that the relationship we used to have is gone now. I don’t need advice just some understanding.
That’s thing about relationships, some people are just in your life for a reason and others, just for a season. Somethings we just need to make peace with because somewhere out there, there may be a reason for why things fall apart…to make way for new things? New relationships? Only time will tell.