[Love2love7]

My husband and I have only been married for 1 year. Before me, he had a gf for 1 year(they dated on and off), he broke up with her in May and met me in June. He asked me to marry him in August and we got married in November. It was love at first sight and since then we have been inseparable. But the issue is with his ex. In the beginning of our marriage I found out that he text her when we got into an argument (it was about her. I sent her a message on Facebook telling her to leave my husband alone because she was still trying to contact him) Then she text him asking him why was I messaging her. He text her back telling her he was sorry that I was acting like that and to not write me back. He also text her saying that he did not want to come home to me.
When I read this text messages I was so angry and literally threw the phone in his face. We had a HUGE argument. I was hurt by what he did.
He told me he was sorry and text his ex telling her to lose his number and that I sent her the message because I was looking out for our marriage. Since then, I have not anything like this happen again. Haven't even heard from her/about her. He's been a good husband but I still think and wonder about his ex all the time. I think about what he did and for the past few days it won't go away! it's driving me crazy.. I think about them together and picture them together.
Help me! what should I do??