My fiancee and I have been together for almost 4 years. We have a 5 year old son (not his) and a 2 year old son and one on the way.
Things have always been pretty okay, nothing fantastic, just average.
He used to make me feel like we were the most important thing in the world and somewhere along the way that stopped.
Recently I have been begging him to actually talk to me, yell at me if he's upset or say anything if he doesn't like what I am saying. I do all the talking, he sits there and says "okay, yup, sorry" but then nothing ever changes. And I do plenty of yelling, which I hate about myself.
Well, I must have pushed him away because he slept with my best friend, my only friend. I feel like chose her to turn to, even though I was begging him to express himself to me. Her marriage was falling apart and he says he tried to comfort her and then it happened. But, it didn't just happen once, it happened at least 5 more times. One time I was actually in the house.
Getting him to tell me the whole truth has been hard, I still don't feel like I have it. I have her side and I don't really care because I have learned through all of this just how manipulative she can be. That aside, it takes two to tango. They are both just as guilty. I just happen to be angrier at her. He keeps saying that he loved me the whole time, but I don't see how that is possible. He doesn't want to loose his family and I don't either. We have agreed to try and fix it. I have chosen to forget about my friend because I just don't feel she is worth it. I don't feel like I have it in me to repair two relationships and my family is way more important than she is.
In the last three days I find myself unable to leave his side. I need him near me to feel better. I want to be mad at him, I am a little, but I feel like my love for him is taking over all my rational thinking. Since he told me I have been stuck to him like glue, I have been so supportive of him and I have blamed myself. I have given myself up to him on more than one occasion. I want to yell at myself, I don't understand why I feel this way. I also don't know how to move on.
Any advice is appreciated.

Is there a reason you have created a family with a man who you are not married to (two, actually)?

Dr Harley has written an entire book devoted to the topic of "Buyers, Renters and Freeloaders" to describe relationship dynamics. He also has the cliff note version of what that is here on this website. I would highly suggest you start by reading that (I would purchase the entire book and read it).

You have created a family out of a Renters situation. Neither you or your bf are in a committed marital relationship. You may have had commitment expectations, but that does not equate to the actual commitment of marriage (a buyers relationship). Much of the advice Dr Harley gives to people who have had an affair wreck their marriage, does not apply here because you are not married.

Your boyfriend cheated on you, wrecked your expectation, and that sucks. Since dating, which is the relationship you chose, is an interview for marriage, your bf has indeed failed the interview in a huge way. I would say you dodged a bullet and move on. Use the opportunity here to educate yourself on what a buyers relationship looks like, since it sounds like that is what you seek. Learn what real commitment is. Learn how to require more for yourself, and find a partner who will give you that.

Stop this. You CAN stop having angry outbursts. There is no place in any relationship for angry outbursts. If you do not like this about yourself (who would???) then stop doing it.

And also, ditch this 'friend' because she is no friend to you. There is nothing to repair here. Never see or talk to this person again.

Have you told her BH (betrayed husband) that your fiance and his wife slept together multiple times?

I was young and made a mistake, but my children are not. The family that I have created now, is one that I love and will do anything to keep together. The fact that I am not married, I believe to be null and void, we have children together. The fact that I love him, I believe he loves me and that we want to work together to fix are problems is a big step and all that matters.
I asked for advice because I am hurt. I believed this to be a non-judgmental place.
To answer the others; I have realized my mistakes and there is/was no good reason to have the angry outbursts that I did. They have stopped and I will continue to work on myself. That friend is long gone. I have no need for her in my life.
Her husband knew before I knew.
Since all of this has happened, we have completed the questionnaires on this site. We found them to be extremely helpful and they sparked a lot of conversation; which is something we severely lacked.

I understand that you want to keep your family together. What has your fiance done to protect you in your relationship? What is his plan to affair proof your marriage, if you ever get married?

Have you read all of Dr. Harley's information on how to pick the right one to marry?

Have you read this?
Living Together Before Marriage: Compatibility Test or Curse?

Just because you wish for the fact that you are not married to be "null and void" does not make it so.
I can wish for 2 plus 2 to equal 3 but it never will.

**EDIT**