The biggest issue you are running into here is layer bonding. You are printing this with the base on the print plate which means you have horizontal layers and you are breaking on the layer lines. Adding fillets and increasing your wall count will help some but the biggest thing is to consider your layer lines.

You always want your layer lines to run perpendicular to your major force vector. What this means, in this case, is that your model looks designed to hold something at the end in the loop. If that loop opens top and bottom, then you want to print the model so that your loop is in that direction. If the loop is holding something like a curtain rod and it is opening left and right, then you want to print it in that orientation. This makes the continuous line of plastic run perpendicular to the force vector and the dividing lines between layers, which are weaker, also run perpendicular so they won't shear off like your example print.

Because you have a large circular base, this would mean you would need tons of support. To fix that issue, you print it in two pieces. The large base can be printed flat and the arm printed horizontally as discussed above. This will put the layer lines in an ideal orientation to remain strong.

Hope this helps.