Bf always lying

Im in a 2 year relationship and me and my bf argue so much he always lies to me about going to work and idk what he does all day his brother lives with him and I don’t really like his brother because of things that happened in the past. I get mad that he always has to lie to me I also don’t trust my bf the other day he forgot his phone in my car and I went through it he wasn’t talking to any girls or anything I checked his web history and found nasty things I shouldn’t have gone through it but he did it to me once someone please give me any advice am I over reacting?