My husband shower a lot of love for his sister after she deliver her baby. I feel jealous and I think I should love her sister like how he love his sister.. But I am too jealousy...

It's common and fine to feel jealous as you really love your husband. Try to put in as much effort for your husband's sister as much as he does, love her like your own sister and soon you will realise that the jealousy will be gone.