Marriage problems - help me

Sorry for the long post…

I’ve been married for 9 years & with my husband for 14. There’s been many times over those years I’ve thought/wanted to leave but financially didn’t think I could. He’s a good person and I’ve tried to feel grateful for him & we have two beautiful children, the youngest just a year. Pretty much since the youngest was born I’ve been incredibly unhappy, we’ve been fighting more than usual and the final straw for me is the language he uses when he fight and I worry now that my eldest is getting older that he can hear him speak to me like that. He’s been living at his mums for the last 4 weeks and I said I’d give it til the end of August to make my decision, he hasn’t made any effort to change anything in that period and at the weekend I told him I was finished & nothing could change my mind. He’s since admitted this came as a shock and he didn’t think I’d go through with it, he says it’s hit home and he’s promised to change all the things that have been destroying our relationship and leading to the arguments…I don’t know whether to give him one final chance and then at least I know I did but in my heart I don’t know that I love him anymore & if it’s too little too late but I feel I owe it to my kids to give it one more shot.

To complicate things further a guy I’ve known since I was a child told me he had feelings for me a few weeks ago, we were with a group of friends so I didn’t and couldn’t say anything in front of them, however we were primary school sweethearts, I’ve always had a crush on him and always felt there was a spark there even though nothing ever happened, even as teenagers. Part of me has always felt we should be together and I’ve fantasised about it for so long so scared of the opportunity passing I messaged him at the weekend and told him I had feelings for him too. I said that my marriage was over but I wasn’t wanting to do anything and wouldn’t be ready to for a while. He said to come back to him when I was ready. I feel like a dick now for even saying anything to him so soon but at the time my marriage was 100% over until my husband has now begged me for a second chance. I would never end my marriage for this other man as I don’t even know that we’d be good together or work out but I always felt I was looking a sign from him to know it wasn’t in my mind and it came. He’s going to think I’m even more of a dick if I’ve to tell him I’m giving my marriage another go but equally don’t want him to think I lied if we stay together.

My mind is just in chaos. HELP ME!