Only over the React patents. They could, however, sue you over your VR system or something but leave you little recourse due to not wanting to lose your React/other FB patent grants.
"...if Facebook or any of its subsidiaries or corporate affiliates files a lawsuit alleging patent infringement against you in the first instance, and you respond by filing a patent infringement counterclaim in that lawsuit against that party that is unrelated to the Software, the license granted hereunder will not terminate under section (i) of this paragraph due to such counterclaim."
Moreover, nothing is preventing you from informing them of your patent and asking that they stop using it. If they continue to, it's clearly willful infringement.