<human>: Well, about 18 months ago I was seeing someone, for the purposes of this post called Ryan [M25]. We were never official, but we fucked like rabbits, usually because he'd text me at stupid o'clock asking me to go round for a fuck. I was used by this guy. He knew I wanted a relationship and would lead me on and on with the promise of one in the future, whilst we continued to have sex.

So now. 18 months on, he is seeing my sisters best friend, Jess [30F]. Whatever, I thought. My sister had moved to Wales, it's not like I had to endure any big BBQ's etc, so I ignored it. 

Well when I was planning my trip to Wales to visit her, she told me specifically NOT this bank holiday weekend, as my Dad was visiting (and me and my Dad do not have any contact and I'd rather not see him) so I planned for the week before. 

I had my mini vacation, all was well and good, until I checked Facebook this evening and she had uploaded pictures and tagged Jess and my "ex" Ryan after they had spent the weekend up there. She had lied to me and my Mum's face about it all, so clearly she knew she was doing something wrong and I just feel sick. She knew how much he used me and hurt me and how much of a state I was when things went south, but here she is, letting him spend the weekend with them, my niece and nephew and sleep in the same bed I slept in not so many days ago!!! I am fuming with her and right now I just want to cut all contact. My mum is furious and says she'll have it out with her but I don't want them falling out because of me. Reddit help. Am I reacting reasonably? Should I confront this? What do? :(

Give me a shortened version of the text
<bot>: Sister invited my ex to spend weekend with her and my family, after lying about the whole thing and knowing full well how much this guy hurt me.