I really feel you, I have had suicidal thought tendencies (never actually had the balls to attempt ****, which I kind of count as lucky honestly) But somewhere in my head when I knew I was too scared to attempt something big I started getting in the habit over a few years of doing self-harm.
I have myself not had a relapse in doing something like it in a long long time...but omg if I am super emotional and in a bad way of things I am sitting there thinking about it.
I always hated how people outside of mental health always just assume if I was cutting i was doing it to end my life. and that was never the case at all!
it sounds strange but for the longest time and still to this day if and when I feel the urge. It's because I have done something I felt was harmful to another person and I wanted to inflict pain on myself in turn, maybe as punishment, or just knowing how badly I had hurt that person and having a relatability to their pain.
but it never was the whole over hollywoodized thing of cutting my wrists a certain direction to bleed out stuff they always want people wanting to think.

I hate it that its so hard for me to open up and talk about self-harm tendencies or suicidal thought tendencies ye by no means are these things pretty or a fun happy topic to bring up in mental health but if you can't find supportive formats to talk about them in some way then they never truly get addressed or resolved the way they need to.