@Sir Sam Vimes,
I'm trying to make sense of what you wrote
You are writing 100 letters a minute I can tell
So, if that doesn't stop who ? A or B, Who slept with 40 guys and has a 5 year old, A or B ?
Mr Vimes, you are driving yourself nuts. If this boyfriend is not mis-treating her and she keeps him hidden to a degree, from all her 'friends' and is happy, but takes you for who you are, perhaps she sees you as someone she trusts, likes as a person, inside and out given she doesn't ever judge you.
There is an old saying, "If you love someone, set them free, if they come back to you they are yours, if they don't they never were".
Forget the signals as you may be reading into them. Having said that, if you want to be honest for once, just tell her in one small sentence, how you feel about her. It's then off your chest, she then knows and you will either end up with her or you wont. Guess what will happen if you don't? You will end up with her or you wont. So honestly, just do it.