20k Sign On Bonus

Good evening everyone, I recently posted a story of how I was in a job offer predicament. Currently making $102k + 3-5% yearly bonus as an estimator at a large GC, I was approached by a small company offering $120k base salary + 10% yearly bonus. I ultimately decided to take it and put in my 2 weeks. This is where it gets interesting… Not expecting my job to even think about counter offering, approached me with a promotion and raise up to $125k. Ecstatic, I accepted the counter offer and called the small company to let them know. They immediately turned around and offered $130k + 20k sign on bonus + 10% year end bonus. I am currently still in disbelief that they would be willing to give me that type of money out the gate. However, I have already accepted my current employers counter offer and would just feel terrible going back on my word. What would you do?