How to be honest about a mistake?

I have always handled situations immaturely and now, I'm in a committed and loving relationship and wish to be more honest and mature. The other day my ex called and I pretended not to know the number, but he left a message. I checked it, played it for my new bf (I know, BAD) and acted all pissed about it. I then changed my cell phone number...

What really happened: My ex had texted me a day before the 1:30 am phone call. I didn't write back and thought that would throw him a clue. When my ex called I pretended not to know the number, then I did what I wrote above. I wanted to tell my BF that I would like to change my number, but instead of just telling him why in a less dramatic way, I made a big production.

Now, I'd like to tell him that I made a mistake. I handled the situation wrong and I'm sorry. I would like to start handling them better and in a more mature way because that was the old me, and I want to put forth a new, more mature me. Being dramatic is a defect for me.

Do I just sit him down and say, look I know it was my ex and I didn't want to be honest because I thought it might hurt your feelings. So, instead I made a dramatic production and handled the situation immaturely. It has been bugging me because this is not who I want to be anymore. I am madly in love with you and wish to show you a more mature side. I am not a drama queen, but I have poor impulse control and stupid ideas. I should have ben honest from the start and I'm sorry. I hope you can forgive me and we can move on. This is an obvious character defect that I wish to resolve. In the future I plan on being more forthcoming...

Tell him exactly that!!
I think you should be proud of yourself for admitting that being dramatic is a problem! But talk to him and explain. I think it will be okay!
Good job!
Good Luck and God Bless

just open your mouth and say it...

Just start with something like
I didn't say this befor, because I thought it'd hurt you but i've thought about not and I want to change the way I act a bit. then tell him exacly what you did and explain how you want to change that part of yourself...

Good luck.

if you still have his number call him back and let him know. I would kill to still be friends with some of my exes, i hate ending things badly, but they just never seem to work out that way. so if you can try not to "burn a bridge".

then you go do that.
you tell him you were sorry for the way you acted, but that he cant keep calling you and bothering you because you are already in a relationship.

Yes a man who really loves you will appreciate that very much. He might be hurt or angry or maybe not he may be just happy you told him. Either way you should tell him and explain it all to him and yes reinforce it all by telling him how much you love him and to really help your case cook him a nice meal (dinner or somehting) have a romantic night and best his best freind. Good luck and its great to see a woman want to be honest. I have not seen that much. Thanks for restoring my faith that they are out there.