Whether to go solo or get help

I'm going solo on a product I'm building and my background is not CS. But I managed to build a frontend (bootstrap), backend (python Flask w/ redis) and hack together something halfway decent. But I fear I can't go to market because I'm afraid of crashes, security and having a mediocre UI.

Learning how to create an amazing UI and do a super rock solid backend is going to take too long (plan to launch in a few months). I also don't want to pay one-time third party services because I anticipate making frequent changes, etc.

What should I do at this point? Do I add a cofounder or do I keep building a bit more to make it slightly more stable and launch this and see what happens.

Also, the crashes and security, is that all in my head or do I have to really account for those things super early on and be able to support all that?