I think I need to apologise

About a year and a half ago, I got into a huge fight with the majority of my friend group.

At the time, I was depressed (suicidal, actually) and the pressure of university led to me taking it out on the wrong people. I said and did some pretty horrible things.

It took a while, but I'm sort of okay now and mostly over what happened. I do miss them sometimes, but overall, I'm glad those people are no longer in my life. Those friendships were pretty much toxic.

But I'm not quite happy with how I left things. Especially since a mutual friend told me the others haven't been able to out the whole thing behind them. I think it might be because I just sort of insulted everyone and left without explanation.

So I think I should apologise to those people. Except I'm not quite sure how to do it. How do you apologise without making lame excuses?

Is apologising even the right thing to do? Or is it just a way to ease my guilty conscience?