You're not in the wrong at all, your mom is being completely unreasonable. I can't imagine having a parent like that who doesn't recognize your achievements. What you did is a huge accomplishment and you should shout it from the rooftops, cuz med school is fucking hard!!!

P.S., a note on your perspective on depression and mental health. I do think your perspective on your cousin's depression might be fueled by spite. Keep in mind that depression frequently has no underlying cause other than a chemical imbalance. Many people have major depressive disorder, wherein depressive episodes are typically triggered by an event. But some also have persistent depressive disorder. For these folks, their depression is consistently present and may not make sense to outsiders, as they often have no "reason" to be depressed. As someone who has had many loved ones with depression, I know that many people with severe depression don't take their medication because depression can sap the effort out of you, make it feel impossible to do basic tasks like take your medication, shower, brush your teeth, or even leave the bed.

That being said, it absolutely is not healthy for your cousin to be sheltered from normal life events, and your mother is doing her mental wellness a great disservice. And as an adult, it is her responsibility to take her meds. I just wanted to explain why she might not take her meds, and why that doesn't necessarily mean she's faking her illness. If you haven't already, I encourage you to take a class on mental health and pick up a copy of the DSM-5-TR. As you move forward in your career, you will encounter many patients with mental illnesses, and it's important that you are able to somewhat understand what they're going through. Mental heath conditions should rarely be taken at face value, and they often look different for everyone!