Kev's problem

When we first started exploring possibly reasons for not getting pregnant within a little more than a year we both started changing our lifestyle to be more healthy, trying to eliminate bad habits. I started exercising every day and eating healthier. Kev cut back on drinking and smoking and completely stopped using his other substance. I was so happy, we were on the road to more healthy family life, even if we still didn't know why we didn't have a baby yet. Then the test results came and we really needed each other and were there for each other. I thought we were both handling things so well. Then I came to find out he had started his substance abuse again. I was so infuriated, but he promised me it wasn't much and he didn't have any at home, it was only a little bit after work. Then just this past weekend we were going to go out for dinner. We would have liked to go to Lanc but that was further than either one of us wanted to go for dinner, so we were going to Etown instead. Kev called to invite my good friend K and her husband A to go to dinner with us. They couldn't go to dinner with us, but Kev says we are going to their house when we go to dinner. They live in Mville which is close to Lanc which was too far to drive for dinner and K & A use the same substance Kev does, so I come to the conclusion that Kev wants to go to K & A's house to get some stuff. I flipped out, I was so mad. Kev admitted that is what he was doing. I tried to talk to him about it, explaining that I thought he had stopped and wasn't going to do that anymore and he wanted to have children so bad. He had told me months before that he wanted kids so badly that he was willing to quit, but now here he is doing it again. All he can manage to say to me while he is playing on the computer ignoring me is that I knew from the start that he did this and he doesn't intend to do this when we have kids. He ends up calling A and telling him we are not going to their house, we then talk more and I cry because I am so upset. He then says, lets go to dinner and we do and have a nice evening.