Feeling useless

I am almost 28 weeks and lately I just feel so useless and incapable. I am sick almost everyday or am so tired I can barley function. Now virtigo is starting to hit randomly and I literally am falling suddenly when it hits. My husband is a Army solider who gets up at 5 everyday for work and comes home for 5 pm if I am lucky. He is trying to help take care of things when he can and I am so thankful for that. But still I am mentally feeling so down lately. This will be our first child and I can't help but worry that I will be a bad wife or mom once he is born. I mentally keep thinking that if I can't handle something like house work now how the hell will it get done once our baby is born. Any advice ladies? Am I alone in feeling this way?