Sorry for rambling about myself right after joining

I have a hard time suspecting people. Even when I try to be suspicious, I quickly forget and end up getting tricked again and again. When I was 18, I had a mental breakdown and had to be hospitalized for the first time. My mother was against it, but I promised I'd pay for it myself with the 1 million yen I had saved from my part-time job, and then I was admitted. After a month and a half of rest and hospitalization, I returned home, and my mother told me: "The hospital bill was 1 million yen, so I took the money out of your account." I didn't know hospitalization cost that much, and I was reflecting on myself, thinking I shouldn't get hospitalized again. After that, I was hospitalized a few more times, and I learned that hospitalization doesn't cost 1 million yen, and realized my mother had deceived me. This isn't the only time my mother has taken money from me, and people around me tell me not to trust her, but I still forget to be suspicious. Has anyone else experienced something similar? How can I learn to suspect people?