Not everything is black and white. You have found an overt grey area in your life. Your insecurities are not his fault, and it is sad you took them out on him. But your insecurities are not YOUR fault either, and its sad he isn't compassionate and understanding enough to help you deal with them. If you love him, my only advice it to be straight up and honest, even if that means a trial parting for a while. If you don't, its too much heartache for you to go through. Think about yourself and your child before anyone else. Does this man make you happy? Will he make you happy in the future? Is he stable and reliable? How often does he do drugs? There are a million questions you must ask yourself. Perhaps do a huge "Pro's and Con's" list, a self survey, whatever. It could, would, help you sort through your muddled problems.
Either way, good luck, and hope your heart is intact when you come out at the end of this, single or still with your man.