Manager calling me a liar for taking sick days

Work has been extremely stressful. For months I’ve been covering the workload of three people. My manager has been under a lot of pressure from the boss, and she’s taken her frustration out on me most of the time.

Because of the stress, I’ve been getting unwell quite often but still forced myself to come in. A couple of months ago, we finally hired someone to help, which took some pressure off. But that new person went on a two-week leave, and during that time I became seriously sick, to the point where I couldn’t even stand without vomiting or feeling lightheaded. I saw a doctor and was told it could be typhoid fever or gastro. I was given a medical certificate covering seven days, but I still decided to come back on day five.

When I returned, my manager ignored me, didn’t ask how I was feeling, and spoke to me as if I’d done something to her personally. During a chat, she even said I was “just performing,” not really sick, that I disappointed her, and that I’m unreliable and unprofessional. Even though she often takes random days off and I’ve had to cover for her many times.

I’ve resigned because it’s become ridiculous. My last day is in two weeks, and now she’s telling my boss that I’m unreliable and unprofessional and spreading her own version of things.

Should I just leave it alone and walk out peacefully, or should I defend myself and set the record straight before I go?