Asking "Advice" on a "cheating" friendship?

“Most of us ask for advice when we know the answer but we want a different one.”
I’ve always found that to be true. Ever since then, I’ve stopped asking for advice. (Seriously…it’s been years…I always think to that statement and it answers my “question” for me.)
So, instead, I am asking to be talked out of doing something. I’d like opinions, wisdom, feelings, thoughts, those sorts of things. What would you do? Why? What would you WANT to do?
Situation (we are all late 20s-ish):
A=Myself
B=Boyfriend
C=Friend

B works nights, I rarely see him. Been living with B for 4 months. Been together for 9. Been “close” for 19 months. Been in love with B the whole time, but shortly before we made it official, he made a choice and it felt like he “cheated” on me. My feelings havent been the same since, and I struggle with it.

I have a son, who has known B the whole time. B has plans to marry me in the future and to be son’s father. Son adores him, he adores son. Great situation there.

Insert player C. Foreigner from work, engaged, started friendship 4 months ago. Will be leaving shortly (exact date still unknown) and will never see C again, might keep in touch via email etc, but u know how that goes.

Have talked inappropriately with C. Have seriously considered cheating with C. Been dangerously close during arguments over B “cheating” to go to C and just do it.

Keep going back & forth between wanting to and not wanting to w/ C. Always think of how it would affect B, how I would lose him if he knew, how it would hurt him and hurt my son, and possibly hurt myself (conflicted feelings seem to distort how I really feel about B, so not sure if I will be devastated or perfectly ok if this happens).

Also think about keeping friendship platonically, spending time with C until he leaves since I will never see him again, and how he can show me places/things I’d never know about otherwise.

Have plans to spend day w/ C while B is at work & son is at sitter’s. B knows this, isn’t thrilled but won’t tell me not to go since he knows that C & I are attracted to eachother. (I would not let him go. I would consider the way I’ve talked with C a form of cheating if B had done it.) So as it stands, I am going.

I do not know what will happen, want to keep it platonic but am scared I will let it go too far. Even a kiss is too far.

I have been cheated on excessively by son’s father. Tore me apart. I cheated on boyfriend after son’s father with son’s father – didn’t feel guilty about it. Didnt love boyfriend either, was more of a rebound/self esteem thing. While I didnt feel guilty, I also never admitted it because I didnt want that boyfriend to hurt the way I had.

I know the right thing to do is to end the bad way I talk to C, and I actually have, but things got rocky w/ B again and I started up again. C goes with whatever I want. The REAL right thing to do would be to end friendship with C. That is what I would expect B to do.

Fears:
That I am missing out on an awesome experience.
That I am missing out on said experience/friendship for someone (B) that possibly won’t be in my life in the future.
That even if B is in my life in the future, that I will regret not having spent that time w/ C.

Dont want to miss out on life just because I am committed to someone. I sit at home w/ my son and do NOTHING right now….work, home, alone all night till B comes home to bed, same thing next day, and that’s it. I have only female friends that I’ve had forever. C is new & shiny…exciting & interesting.

I think that covers it. I’m ready to be talked out of this so I can do the right thing! I keep hoping there is a technicality I am missing…a gray area yet to be seen. Show me if you can find it, or please try to convince me that the trip would be wrong.

Ready….Set….Go!!!