There's nothing embarrassing about it at all! You had the disadvantage of mental health problems that other people may not have had, it's not a matter of laziness or carelessness, it's a genuine problem that impeded your studies. Also, the past year has been more difficult than any other year, so no one would judge you for retaking, I bet you that so many people will be retaking like you. You don't have to tell anyone if you don't feel comfortable, and there is no point in judging yourself! Personally, I think it's a real achievement that you got into university, tried your first year and experienced a set back and then still had to courage to do the year over again.