He lied and cheated

I live with my boyfriend and on his way home from work he told me he would be staying with his grandparents because his grandma was in really bad shape which I believed because she is in her 80s and not exactly 100% so I packed him clothes for work the next day and stuff to spend the so when he got home at around 9 he would just leave right away because it was an hour drive. He comes home kisses me we talk about our day and he leaves. Instead of his grandparents he goes to another girls house who is a bit older that him. He then proceeds to change his mind about spending the night and comes home at 1 in the morning. I know he prefers older women and I’m 10 years younger than him (no judging please). So that’s always been a huge self esteem issue for me. I go through his phone which again I know is bad but I always see him texting someone and he try’s hiding the screen. Plus he’s gone through my phone so I only thought it was fair, right? He’s telling her she needs to buy Plan B and that he can’t afford another kid ( he has a daughter with an ex 11 years older than him). We just bought a dog and plan to buy a house together this year. The obvious answer would be to leave him. I currently have NO money and I messed up bad with my family so I can’t go running to them. I just needed a place to rant because I was tired of keeping this to myself and not having anyone to talk to. I’m hurt and I can’t even look at him hardly all I can picture is them having sex and him kissing her and it’s really messing me up.