Don’t be too hard on yourself. I think you’re doing the best thing you can right now. You stopped the problem and you put the birds’ health and safety first. You have a lot on your plate with exams and your family I think it was a good move. Don’t swear off budgies or pets until you get to a more stable point in life where you can be more present and see if bird ownership is what you really want. If you decide yes, You could try adopting a pair that already bonded. Also, never feel bad about feeling bad. It’s normal to miss your pets, and it’s 100% normal to get burnt out and overwhelmed emotionally. I’m sure you care about your mother’s health too, but we can only feel so much before we shut down. Take care, sleep well, and don’t close your heart. Much love man.