People who take cannabis or other drugs always like to kid themselves that the drugs are harmless, but over time they all cause dangerous changes in personality and behaviour. You're obviously a personal who has worked very hard to make the most of your life and you can be proud of your achievements. It's hard to lose somebody you love but in such cases you need to step back and ask yourself how this person will be affecting you in one, two or five years time in terms of where you what to be, and whether this person is nurturing and supporting you or trying (unconsciously or not) to destroy everything you have worked for, and negating all your achievements.
Yes, you do deserve better. Perhaps after your marriage breakup you were more vulnerable than you realised and perhaps were subconsciously not looking for all the faults your new boyfriend had, which have now become apparent.
Be grateful that you are now sufficiently recovered and are feeling more more self confident to recognise that you were being used and being hurt and try to move on. More importantly, give yourself some personal space before embarking on another new relationship. Work out in your own mind what kind of person you want and need and feel compatible with. And until that person turns up, don't allow yourself to get too deeply dragged into another relationship., You can be strong enough to go it alone until that happens, and by doing so, you will start to feel more confident being a single person rather than just being with somebody else, no matter how terrible their faults, just because you don't have the confidence to be alone.