how do I know if my boyfriend loves me and isnt just cheating on me?

I have been with my boyfriend for 7years we met in high school. we have always had are little fight but alway get back together. about a year ago we broke up he was up set we were both crying but I thought it was for the best. we were broken up for about 6 months. I relized how much I still cared for him, but it didnt look like he cared much for me. he was going out and partying like I have never seen. he hung out with one girl all the time he went after her she works with him. well we ended up talking again and are trying to work things out he just keeps saying he doesnt want a girlfriend that we need to work on things. he still lies to me he said he was hanging out with a friend at his house and wasnt he swore to me and promised. the next day he called me by mistake. I heard a conversation between him and his mom saing he went with that girl out. I asked him about it told him what I heard I even found the a recpit. to this day he still says it never happened, even through I know it did. we have been working things out for 4 months know and everything is the way it was but he doesnt want to call me his girlfriend still. we had a big fight the other day and he got his mom into it she doesnt want me around you know its a mexican family. she doesnt even want him to talk to me. the other day he said we was getting off work at 11pm he always gets out at 1030pm ha said he was going to take a shower and call me at 12am he didnt I called his house his brother said he went out with friends. I know that girl was there. he called me at 130am he said his brother was lying but I dont believe it. I know I am a jealouse girlfriend but its because I am afraid that I am going to lose him. I always acuse him of cheating on me but its because of all these lies I dont know what to do anymore I just want the same guy back. after this brake up I think he just likes the fact of being single I have been with him sence 9th greade what do I do is he cheating?