How do I write a sympathetic villain without making them too sympathetic to the point that it just comes off as easily forgiving their actions?

I always wanted to write a villain oc..but I don't wanna make a villain that's just evil for the sake of it, i want to make a villain that is sympathetic and will help you understand why they're the way they are, but I'm nervous that ppl will say I'm trying to excuse the villains actions or im whitewashing them

What should I do?