Husband diagnosed with epilepsy sister thinks i should leave him since he is now on disability...?

My husband was diagnosed with epilepsy about 4months ago and soon after was on disability because the epilepsy plus his rheumatoid arthritis was too much and the highway patrol couldn't risk keeping him on because if he had a seizure while doing anything it could mean his life or that of others. Well anyways we have a two year old son together and i am 7months pregnant with our second son well my sister came over while my husband and son were sleeping and said i should divorce my husband and get a real man that isn't 25 and on disability. Well we basically got into a screaming match which woke my son and he came out and asked what was going on and my sister being any idiot told him she was trying to get me to divorce his dad in which he turned around and ran and woke my husband up and told him and was screaming and crying and i just made her leave and now my husband is mad and doesn't want me to touch him! He thinks i am going to leave him now which i am not i love him so much and i love our kids how can i get him to realize that i am not going anywhere? What should i do? Advice?