He constantly lied to me for 3 years

I been with my fiancé for 3 1/2 years now. We just got engaged 3 months ago. Since we first got together up until 3 years of being together he pretty much would lie to me about his real thoughts and who he really was. Like he would always tell me what I wanted to hear, lie to me if he knew I’d get mad about something, tell me he thought one way about situations when he really thought a different way, we would have convos about stuff we are okay and not okay with in a relationship to set boundaries and he would lie and tell me what I wanted to hear yet still do what he wanted opposite of what he would tell me. In past convos he would say he wouldn’t be okay with certain stuff so I figured we were on the same page then later go do that same stuff and get mad at me for getting upset and tell me he never said it wouldn’t be okay. Tell me he wouldn’t do something yet go do it anyways behind my back and not tell me. You guys get the point. Anyways he was doing this for the whole 3 years and claims he finally stopped doing it (lying and only telling me what I wanted to hear) but all that created a trust issue for me cause I can’t even believe him when he tells me something or gives me his opinion on something or I feel like he’s hiding small things from me on purpose. Forward to now, it’s been like 6 months of him claiming to be honest with me about himself and I feel like I’m barely getting to really know him and I still have trust issues towards him and he doesn’t get that he says I need to get over it and him lying about his personality and who he really was isn’t a big deal for me not to trust him this much. Gets mad if I ask one too many questions and gets furious with the fact that I don’t trust him. He says it was little stuff he lied about and says it’s not a big deal and won’t give me time to trust him without getting mad at me. Says it’s been months now and I should trust him by now etc. FYI He never cheated or anything like that. I didn’t get into to much detail with the story cause I didn’t want to make it longer than it already was but I need opinions on the situation, how to help the situation, learning to trust him, getting him to understand my side. Any feedback will be helpful! Thanks guys. Please no negativity.