From your description, it sounds like the other person is mostly at fault. A vehicle pulling onto the road from the shoulder has a duty to make sure the lane is clear before proceeding. Therefore, the other party is at least partially at fault.
If you were speeding, even just a little, that could be considered as contributory to the accident
. If you failed to slow down as you approached the vehicles on the shoulder, as might be reasonably prudent, that could also be considered contributory.
Missouri, like most States, is a comparative negligence State. This means a court would determine what percentage each party is responsible for the accident and assess damages accordingly.
In all likelihood, it sounds like you would be held at least partially responsible if the report said you were not attentive. Of course, if the case does go to court, you have the right to challenge that. But how a court decides that question of fact is not something that can be predicted with any accuracy here.
In short, the likely outcome is that you could be found partially responsible, but the plaintiff's own negligence would probably substantially reduce any award.
I hope this answers your question.
Please keep in mind that information in this forum is for informational purposes only. It is not legal advice and does not constitute creation of an attorney client relationship. Before acting on any such information, you are always advised to consult with an attorney licensed to practice in your jurisdiction who can take the time to review all the facts and laws relevant to your situation.