Is my wife cheating?

I guess i might be insecure because my wife always dated younger men and im not so young anymore. Shes always dated a variety of men aging approx. 8 years younger than her. When i started dating her i was 22 and she was 30, now im 33 and shes 41.

Me and my wife had an arguement one night that hasd nothing to me with us. Her daughter 22 yrs old started an arguement by yelling at me and when i lashed back at her her mother started argueing with me. It led to her going to stay 3 nights with her sister with her daughter who was pregnant. When i went over there one day they wouldnt alow me to come in which i thought was strange and my wife who had just came from a 3 hour drive with me to talk things out wouldnt come outside. She comes back home the next morning and her daughter stayed there and fell out with my wifes sisters son who is 39. Later my wifes nephew told my wifes daughter's boyfriend that she had been sneaking a n ex boyfriend to the room where her and my wife slept. But it is not known if this is during the time my wife was there. While my wifes daughter boyfriend was away out of town on a painting job she kept toggling the 2 boyfriends.
So 2 months later Me and my wife fell out again about the day she left home and she went to stay with another nephew for 5 days. I told her she didnt have to leave but she stated she couldnt stand me anymore. 5 days later she comes back home and when i went over to her nephews to help her get her things her totes was in the basement as well as her alarm clock. But she told me she slept there and then later told me she didnt sleep there that she slept upstairs. I asked her then why is your alarm clock downstairs when you know you have to get up for work and she stated that her nephew wakes her up. It was apparent that she gets very nervous to even have me go over there with her to grab her things so she never got the rest of her items. Its been 6 months. She secretly got a telephone from her sister to use over there and it wouldnt of alarmed me but she never spoke of it and her nephew told on her accidently because she left it on the kitchen counter. This was placed there a day after she moved back in with me, and stated she never used it. So when i asked why you take it back there she stated so her sister can come get it because she dont need it anymore. Its many lies shes telling me i can tell.
she gets frustrated anytime i ask her and keep saying "im a good woman, im a good wife". She contradicted herself so much but has mastered the tales of the events over time. I cant get her to tell the truth no matter what technique i use. Now she acts like she doesnt even care, and says she wants to go forward with me but other times says she doesnt wanna be with me. I think shes only worried about how she would look to others she's trying so hard to convince she's the good 1. Thats all everything is about to her to prove shes the good wife and im the bad guy. Im also alrmed about her costantly repeating this.
Even thoe her daughter is an adult I feel it will be wrong to trick the truth out of her. She cant lie at all and I find it hard to resist.

Dont get me wrong i have done some awful things. Before I got married to her I cheated on her. I try to prove to her iv'e changed by not going out at all or doing anything that doesnt involve her. No matter how i approach her she says she doesnt want to hear it and that her grandchild is all that matters. So I messed up bad, this was about 8 years ago. B4 i cheated on her she would always accuse me all day everyday of cheating when i wasnt and i guess one day i did. It was with my ex friends girlfriend. A man i called my brother. Being a kid i guess. Before she started dating me she dated him a few times he was about 17 and she was 26. I was ok with her past until he kept throwing it up in front of people to embarrass. he started getting jealous of my life, and then i got tired of it and made this huge mistake. But i wish she wouldnt have married me sometimes.