NMom trying to sabotage husbands immigration

I've been very low contact with my Nmom since November but she still was on my husband and my FB. Yesterday she took offense to something political he posted and absolutely blew up calling him all sorts of vile things. I asked her to stop or she would be blocked and she unfriended me. This evening she texted me saying she had called immigration today and was obviously trying to upset me and use this as a threat. We used her as a character reference 2 years ago (stupid, I know) when hubby filed for citizenship and he is still a resident. What potential does she have to potentially fuck things up for his immigration process?