Need help

For basically 2 years. I jut recently started school. I am a junior & have some difficulty going back so he said he would support me. He graduated last year & is commuting. He hasn't started yet until September 12th. Around the time school started a lot of things happened to me. My dad cheated on my mom, & my dad currently lives in the living room. They never tak & dinner is just horrible. My grandma had 2 heart attacks & her pacemaker gave up. (She is doing better). & all this with school starting, which is already pretty hard for me. My boyfriend at this time starting taking to a girl named McKenna. A girl he had talked too before & we discussed & he promised he would never talk to her again. (I don't like this girl because she is very flirty & has always wanted something with my boyfriend). For some reason I had an instinct & brought it up to him. At first he lied. He lied a lot actually. First it was that he hadn't talked to her at all. Then I kept nagging him & he said he had talked to her over a month ago about work stuff (they work together). Just last night, I kept nagging him & he laughs when he's lying so I knew. He confessed that he talked to her for a while & ended last week. & today he told me that she is a good listener & that he vents about college. He then told me that I don't listen & don't have time for his problems. He said he would stop but I don't believe him. He has lied to me so much. & much more than I have explained In this paragraph. Is this wrong? What should I do? If you have questions please ask. I'm very worked up so I might not be as clear as I want to be. Please help!