Best triend or is she using me?

I don't have alot of friend's because i have trust issue's with people me and amie have been friends for almost 3 years and we meet at work her husband and he do everything with me and my husband our kids play and go to school together her husband lost his job and here lately they are always at my house they invite theirselfs for dinner and never help clean they dont and havent had gas on at their house since ive known the so they take all their showers at my home they come and sit on my pc all day and the other day they asked if we wanted to go play pool at a local bar but when they got there my husband bought the first round and they informed us the dont have any money for pool or anything else i dont feel that they come over just to visit there is always motive im taking care of a dying mom that ive quit my job to take care of her and we have 3 teenagers living at home my husband is in the oilfield so we do preety good and they see it are we being used for what we have? now my husband has tried to get her husband to go to work with him but he makes excuses what do i do? do i need to tell them how this looks and feels or am i overeacting?