T.M.
Well, I must say I am quite jealous that your husband was even open to buying patio furniture and a BBQ in the first place. Hee hee. Pretty ambitious shopping trip for the day- esp for a husband.
Seriously though- sounds like communication 101 troubles. Try not to take your husband's insensitivity with you as a personal attack. From your story, I get the sense that he gave up on the shopping out of his own frustration with the situation. And your lashing out was yours. My husband and I have these situations a lot when we have not spent quality time together for awhile. (ie: dates, sex, laughing together) If that's not the case then file that away because the family that doesn't play together doesn't stay together.
But, as a Mother of 3 I know that long shopping trips are out of the question. As parents you "both" needed to consider the family as a whole. Maybe in the future, scheduling a play date, babysitter, or having a grandparent watch the kiddos might have help you two to reduce the stress, to stay focused on the task and make quicker decisions.
Hope you all are cooking and eating in the patio real soon.