Should I be mad?

So my fiancé said he had to leave for a a little bit because he had to help a his friends dad unload something.. well he left and was literally fine for like 5 minutes so I knew something what up, you don't go help someone unload something and are fine for a couole minutes.. especially when it take like 5 minutes to drive there.. so I secretly go threw his phone, I told him my phones as dead and just wanted to get in snapchat. So I get his phone and he does up to get a drink. Well I open his messages. To find out he went to his one friends to buy weed of off him. I knew he smokes but he told me he was done buying it and not going to smoke anymore. Because I pregnant. He doesn't have a job right now so we can't offered the extra money. So 2 lies. He lied about where he went and he is still buying it. I'm trying not to be mad but I don't like to be lied to. What are your opinions? He complains to me trying ovation have has no money got the thing he needs and to support his kid but I goes and blows it.. it just pisses me off💁 I love him so much and he really is a sweet guy and treats me like gold but the way he handles money and tries to sneak around me I can't deal with that.