What should I do, stay or go!?

I have a GF in her 40s (we are same age) who has had bad relationships in her past. She was married to a abusive husband for 20 years then proceeded to get a fe lossers along the way that would have her take care of them. She isnt materialistic she doesnt care about money she just cares about being happy. I am a professional man that has his act together, i have been thru some very distructive relationships however I believe in love and that you can have a good relationship so I do take the risk. I have been with her for hmm about 4 months and everything seemed to be going good, I would stay with her because she stated she hated to be alone, I didnt really mind because it was alot of fun. I am a good man, I think maybe to giving sometimes. She started the early stages menapause and things have changed she stared to have a lower sex drive and became moodie (she has a very stressful job). She asked me not to stay as much because she felt smothered a bit and was getting aggitated with me for little things, I did so because i understand. During the weekend after making love we were holding and her ex BF who lives far away and has no means to take care of her kept texting her, now i know she was chatting him, she knows i dont like it however I elected the best thing to do is voice my thoughts to her and let her decide. She told me before that he was just a friend and that they were together for 5 years (broken up for 1 year because he moved and cheated on her). When I asked her why was he texting so much she said she didnt know, I asked her why she didnt just let him go and not talk to him, she stated taht she couldnt just let him go that she cared about him and his2 kids (these kids dont even live with him), I asked her what do you mean by caring for him is it the same as me? She said she didnt know taht is why she is learning that it is ok to be alone that she was trying to do it right with me and figure out what she wanted. She has been very honest she told me in teh past she would have guys move in back to back but she wanted to do right by me, she has told me everything and she stated she has never been so honest. I am hurt by this I am also not into living in the shadow of some looser. She tells me that I should not worry about it however I do. This EX says he maybe moving to where his daughters live to help with their situation its closer but still a state over. I told her what if he wanted to visit what would she do, she said she didnt know. I didnt like this answer and stated i would not be around if she let him, i know this is to the point and laying teh cards down but i was shocked by the answer, I do love this gal but i am seeing flags fly up here and there. Please advise...