I think you are very confused. It probably would have been better if you didn't enter into a new relationship when you know that you are not entirely over your ex. It is unfair to your current boyfriend if you are with him while missing and thinking of your ex. Regarding your ex, if he regrets having dated you and he tells that to everybody, then that is not a sign of maturity. So in my opinion, you are better off without him. If you truly love your boyfriend now, you will focus on him and your relationship.