Ive been dating my boyfriend for over a year now,we have a very healthy relationship and hardly argue over anything, however his little teenage sister is the main cause for all our arguments that do occur.Me and his sister are very close in age we both have our birthdays days apart and associate with similar friends however the majority of theses people i have either disassociated myself with or become distant friends with because of here bitching about me to them,his sister is currently a single teenage mother and a high school drop out so she spends the majority of her time at home,she has suffered abuse from school members during her pregnancy and after because of the father of her child.The problem occurred when i wanted my boyfriend to visit my family because i was finding myself visiting his too often and him very little, all of a sudden she starts playing up around her mother(who has very high blood pressure and is often ill) and refuses to stay home and help out around the house and look after her own child, she has on many occasions ran away leaving her child unattended so my boyfriend will not be able to leave the house and visit me, she has and still does make side remarks towards my boyfriend when im present to test me(she has no respect for him).I feel although she is in constant competition with me when it comes to hair styles makeup clothes everything really, she even wears brand new clothes when i come around just too show off.The worst incident so far is the facebook one, were she made a facebook account and was stalking my profile page for months watching what pictures i was adding, viewing pictures of me and my ex boyfriend i was tagged in then and saying they were resent pictures to her family( the older members that dont use facebook) the worst part is she cant even use facebook properly and on numbers of occasions had my name as her facebook status and like the page of my name.Its got to the point were i have been confronted by her own mother about her obsession over me, they put it down to her being jealous of them liking me so much but i know its bigger than that.I understand that being a single teenage mother is hard but im puzzled as to why she is so very focused on being jealous of my life in particular i Havant said or done anything to start this obsession off, i realise we live very different lives things i am allowed to do and go she wouldn't even been able to dream of, even if she did or didn't have a child her parents would not allow her to do so.I have come to the conclusion that she is jealous of my image,friends,boyfriend education, financial status and background etc.. but I am growing sick and tired of her obsessive spoilt behaviour she is ruining my relationship with her childishness she is doing ever thing in her power to make sure he is not able to interact with my family in anyway or me! i have no idea where to go from here advice needed!