I will hurt you because of my mental illness
I will ghost you. I will cancel plans at the last minute. I will break promises. I will leave early.
Saying "because of my mental illness" is not me trying to excuse myself completely. It's not me denying that you are being hurt. Or that I am the one doing it. Or that I am the one responsible. And I'm not trying to imply that you should always put up with it at the risk of your own well being.
Just know that I detest when I hurt you, even while I'm doing it. Sometimes I don't detest it because I'm instead apathetic, and you think "how can he not care about what he's doing"? You're right. When I'm not apathetic, I also detest the times I'm apathetic. I detest the periods when I am insensitive during the periods when I'm not. I'm still not saying that my intention or desire makes up for the committing of the act, just please know, at a baseline, I don't want this for you. Not just wanting not to be depressed for me, but for you too. Now granted, this is true for everyone. No one matches their desires with their actions 100% of the time, so what's the point in stating this when it goes without saying?
Because it will happen. As long as these mental illness problems stick around. The frequency will change, sometimes to be very seldom, but the past does not indicate that these mental illnesses will be gotten rid of, and believe me, I will bloody tell if you if they do. My ability to handle them will fluctuate. Sometimes I'll do something stupid. Sometimes I'll do something really stupid. Sometimes I'll do something downright idiotic. Hold me accountable for all of them. But when you bring them to me, please, understand that, indeed, my motivation behind my actions does play a crucial role. But also, sometimes, it's just because I'm sucking at handling life and it has nothing to do you or the situation.
When the frequency changes, when I become completely radio silent or don't act reliably, you have no obligation in continuing to engage in harming yourself by interacting with me. I'm not saying you can't, I'm saying you are not obliged to. If you want to reach out, please, do. But not if it's going to cause you harm but you still feel like you should. Take care of yourself. Always.
There's a crucial distinction between "excusing" and "explaining". Excusing is trying to say "I'm less responsible and here's why". Explaining is saying "I fully accept my responsibility, I'm just describing the circumstances for the benefit of understanding the cause and effect that lead to this situation". One carries a moral implication, the other, a contextual.
I'm not excusing future incidents. I'm just explaining them. My motivation for doing so is in hopes that knowing the context, you may be hurt less if only by, say, knowing that it wasn't personal. Or sometimes not, sometimes the context means diddly. But if it has the possibility to not hurt you as much, and thus maybe not harm our relationship as much either, then it's worth saying.