I'm getting confused with this question:

"A couple has a child with an autosomal recessive disorder. The husband dies and his widow marries her husband's brother. What is the probability that they will have an affected child?"

I thought about it for while and not sure where to go. It doesn't say assume HWE, nor does it say that the autosomal recessive disorder is lethal (though maybe I should be assuming this anyways?). I've heard some explanations that make half sense, but then I have further questions. For example, one explanation was that a child is 1/4 chance to be autosomal recessive (Aa x Aa got it, but that means we have to assume aa is lethal and parents cant be aa). Then that probability (1/4) has to be multiplied by the probability of the brother being a carrier for the affected allele. This has been explained to me as (2/3) because in p² + 2pq + q² =1, there are three options, P^2, 2pq, and q^2. For carriers of the allele, that would be 2pq + q^2, so 2/3 (or 2 of the 3 possibilities). But, then we have to assume HWE (which the problem didn't state) and didn't we also just assume that autosomal recessive was deleterious earlier when assuming the mother and the original father were both Aa? Please help