First of all, it's all about how you want your startup to be perceived by a potential employer, not how you perceive it. After that, it's about what the Proventil employer thinks when you talk about your startup, not what you want to talk about. So, I'd give a piece of advice on the topic, without any hope to give a profound and complete answer:
Convince the potential employer that the risk they are going to take stands within boundaries. You've probably heard a lot about tailoring your CV to a certain job or pool of jobs. It's the right time to do so. Research your employer and try to understand if they allow or even expect an employee to be an entrepreneur-esque one (PaEi, according to Adizes, if you like), or are they too giant and slow to hire somebody who would like to jump over his head and will try doing it the moment any opportunity appears and they'd better hire a person who sits on his butt and does his work from 9 to 5 (PAei). The riskiness scale is unique for each employer, and you should be prepared.
Calculate your further commitment to both of your jobs, in continuity. You want to grow, don't you? So you may get in trouble if, at first job, you are navigated to or expected to go by yourself to a new position, while the second one suddenly demands more time than before. There are a lot of tradeoffs all the time. You'd want to literally write all possible risks and obstacles down and calculate possible outcomes. From that perspective, rethink the balance between the two jobs.
Show that you are proud, don't show that you are busy. The second job isn't actually a project but a long-term continuous self-employment, isn't it? So, at first thought, you should put it right after the latest job as an employee, at your CV. But be sure this will certainly lead to thorough riskiness scale assessment. So you should better not show off and mention this job in a more lightly manner.
Just remember, the CV isn't the end. You'll get an interview, and probably more than one, with different employer's representatives (recruiter, technical expert, manager, security, etc.). So you'll have plenty of chances to talk about your second job and explain the situation in detail. You need your CV to catch attention without causing suspiciousness. So, I'd make a conclusion that the optimal path is to mention your second job in Other Projects section while getting ready to pitch it the best way.
