From your description of lanes, I presume you are from the US, so I preface my reply by stating I'm from the UK - and a police officer! From your very honest account, the answers quite simple - I'm afraid you're the one technically at fault. Why? You cut in front of the other motorists path, and most importantly, you admit you never saw her, creeping into the realms of due care and attention. Simplify it like this if you like: if you HAD seen her, would you have still performed exactly the same manoeuvre? If the answers "No" then it was your fault for not checking the lane. In fairness to you, and in your mitigation, she could have been more prepared for you to pull back in, and most good cyclists would be. The fact she didn't however doesn't negate the above two facts though. Additionally, your mitigation regarding the fact that you didn't check the lane as no car could fit in it is an explanation, but as you've discovered, you should always check for those damn bikes! Please don't take this as a 'flame' - you asked for an honest answer. I applaud you for stopping and showing the care and compassion you did.