I'm a 24-year-old female in a relationship with a 25-year-old male.

I'm currently in a relationship with my fiancé, and we have a one-year-old together. He seemed perfect, and I never suspected he would cheat. However, over the past year, we’ve grown apart, and I've noticed a change in his behavior. His family has tried to interfere in our relationship because they were taking money from him and didn't want me to find out. He’s never had a relationship last this long or moved out of his parents’ house until now. He works hard, keeps long hours, and earns a good income. Unfortunately, his family has been undermining me, making negative remarks, as they managed his finances without teaching him about them, which held him back. Recently, I’ve caught him in several lies, and I felt a noticeable change in his attitude. I’ve also been dealing with postpartum issues and insecurities. When I checked his phone, I discovered dating site links on his Instagram. I deleted those, but I suspect his sister has put spyware on both our phones. I later found some other concerning signs, including a search he made at a gas station about how to pause Life 360 location sharing. Even during my single years, I rarely used dating apps, except for Tinder, but now it looks like he’s been on some casual hookup sites and Reddit. I also found evidence that someone requested to delete his information from Google. I have access to his emails and phone, but it appears he’s been hiding things using platforms like GitHub and Gemini. If anyone has advice on how to navigate this situation, I would really appreciate it. I don’t want to lose my family, but I need to know the truth, especially since he claims it’s just his sister involved.