There is no shame in walking. Even a flip flop hub has three speeds. Left side, right side and two feet = 3 speeds. When you choose to ride a singlespeed or fixed gear, you voluntarily selected a form of cycle limitation for the reward of the experience such limitations provide.

Any hill that is steep enough can make the best of us walk our fixed gears.

The chief error among newbies is gearing too high for an aggressive look (ie fashionista fixie).

The better option is to gear in mid to high 60s and learn to spin. Not only is it better for your cardiovascular health, its better for your knees and prevents joint issues. Lower gear ratios also make it easier to slow yourself down by resisting the turn of the cranks. Once you pay homage, we might even initiate you into the cult by sharing the secret wisdom of obtaining better skid patches so you can skidz (whatever that means, I ride with two brakes).

"There is no failure, only feedback." - Art De Vany

As you get stronger, your needs will change. As your skill improves, so will your gear ratios. Learn and adjust accordingly.

At your present weight, I suggest lowering your gear ratio before you blow your knee out. Remember, spinning burns fat and generates less lactic acid in the muscles than mashing thereby reducing recovery times.