Walking away from my marriage....

Back in September my husband wasn't sure he wanted to stay with me. He said he was unhappy an he didn't know how he felt about me. When this was going on I left for my moms for a week to give him space. He ended up kissing a girl, but claims it meant nothing. He just wanted to see how he'd feel not being with me. Our marriage was on the verge of ending. Around the holidays things started getting better. An divorce was no longer talke about an we started making future plans for us an our son. After thanksgiving I found out I was pregnant (2months). He seemed happy an like everything happened for a reason. I thought we got threw our rough patch an was moving on with our lives. Idk why I went threw his phone tonight but I did. The girl he kissed was texting him. An called him twice. She moved to NY we live in Maine an supposedly was only calling to ask him to have a mutual friend get her mail from her po box. Apparently she couldn't get ahold of mutual friend. I don't believe him tho. I don't think he should talk to her. The texts didn't make sense seemed like messages were deleted. He says I'm crazy an that if I feel he's lying then I should just leave. He said if I'm going to be paranoid an crazy then why should he prove to me he isn't doing anything wrong. So I guess that's it... I guess I should just divorce him an raise my kids alone. I been crying for hours an idk what to do. I love him an our family so much but I don't want to feel this way... I know rveryone will just tell me to leave him. I just wish it didn't hurt so much. N I might be ending my marriage an he may not be lying to me idk. I'm just so broken