My friends and I have dealt with Facebook before in various capacities, and I can tell you that they play DIRTY, and if it comes down to it, they won't hesitate to use the aforementioned PATENTS license in their favor against you.
I know many stories like this; Facebook M&A meets with the founders of a promising company under the guise of a "we're about to acquire you" only to have Facebook copy their companies and then follow up with Facebook's lawyers knocking on said startups' doors to shut them down.
As such, I will not touch Facebook with a 10 foot pole, and I strongly recommend, from personal experience, that you do the same with your company.
I know many stories like this; Facebook M&A meets with the founders of a promising company under the guise of a "we're about to acquire you" only to have Facebook copy their companies and then follow up with Facebook's lawyers knocking on said startups' doors to shut them down.
As such, I will not touch Facebook with a 10 foot pole, and I strongly recommend, from personal experience, that you do the same with your company.