Hello! Lovely to hear you are looking forward.
To me, friendship is about the long haul. Some of my friendships go through fits and starts, where I don't see as much of them as I used to. I know they still think of me, and that they know I still think of them. We come together and drift away in cycles.
Don't mourn the loss of friendships if you want to keep some of them. You're AWOL period is small in the scheme of things. You can explain as much as you are comfortable with. Just say things have been tough, but you hope you can pick the friendship up again. Take action to rekindle them.
I always think we are so busy our own lives, it is hard to notice when someone has stuff going on, and then you leave it a while, and then think it has been too long. In reality, it isn't too long, and the other person is pleased to hear from you. See how the conversations go as to how much you you want to say.
If you were a real life friend of mine, I'd be relieved to hear from you, would be happy to carry on, and would welcome you back. Reach out, and believe in yourself.