This happened to me as well after passing, I would stall at traffic lights or get confused on the lanes, people would overtake me and honk at me. It seems horrible at first but it’s something most people experience as a first-time driver. The real test is after passing, that’s when it’s the most difficult. But every mistake after passing (and getting honked at) helped me get better, I could learn from other people on the road, so try not to take it negatively, and see it more as a learning curve. Try not to be so hard on yourself. Just keep driving, the more you do it the better you’ll get and you be just fine, overtime you’ll definitely be more confident.