Am i wrong to think that its not ok for my ex to be seeing someone within a couple of days of breaking up?

Me and my now "ex" girlfriend have been together for nearly 4 years now. Things have been abit up and down since i moved with her to another town so she could pursue a new job. I had to restart my study. Not even a week ago (6 days to be exact) we broke up. Prior to these 6 days, she was on a course where i couldn't contact her (rules state there is no communication on this course) for 8 days. During these 8 days, she had met a person she shared a similar understanding, on what grounds i'm not sure, but it was enough to end our relationship as soon as she got home. She had her reasons i understand as our relationship had been rocky, both of us contributing factors, but what gets me is that she's already seeing, staying, with this new guy, whom i offered to meet and did upon our first meeting just to say hi. Is it wrong for me to feel angry and resentful towards her, as i still do care and love her, she says the same, but so soon. Its not even been a week!!