Need advice REALLY BAD!!!!

Ok so i am having a very rough time right now with my boyfriend and i don't not if i should follow my heart or my mind, We've only been together for 6 months and we already live together our relationship moved pretty fast defiantly faster then it should've but i feel like im in love with him and that he could be the one but recently i've been having doubts. He has 2 kids , a girl and a boy and he shares custody with their "mom". Now the problem is when he texts her. i don't have a issue with him texting her ONLY IF its about the kids, because i feel like there is no other reason to text her and he claims he hates her so much and only deals with her because of the kids yet he texts her things that he shouldn't be for example we came up with a topless cleaning services and he texted and told her that he wanted her to be the face of it and he wants her to be his business partner when it was my idea. Another time he texted her and was telling her he missed her and just venting to her getting all his lovey ass feelings out , shes sent him pictures before , and somehow some pictures of her ended up in his gallery and he acted like he didnt know how they got there and he told me he deleted them come to find out they were still on there then when i said something about it he said he forgot and then he deleted them. There is just always a accuse for why he is texting this shit when he knows how i feel about it's disrespectful to me and it make me look like a dummy because she knows we are together. And the crazy thing is most of the time she doesn't reply or she says "Just stop" it's like he craves her attention or something and i dont understand. But all of these situations were in the past and he promised to only text her about the kids and today that promise was broken i seen another text that he sent her telling her that he was moving and he wanted her and the kids to come with him(we planned on moving to Cali) and then he sent her a video of Monsters and Men Love Love Love song and then tried to give me a stupid reason for why he sent it. He says he loves me and sometimes i believe him because his actions change and then out of nowhere he does something that just hurts me so bad. My heart is telling me to stay and work it out because we are still early in the relationship and my mind is telling me to leave because im only 19 he's 26 and i shouldn't be dealing with this. I need advice soooo bad.