I am having a hard time grasping how to simplify circuits with diodes (assuming a piecewise linear model w/ a turn on voltage of 0.7 V). I have attached a picture of a circuit with a 2 diodes in series and 3 other resistors in the circuit. I am having trouble trying to figure out where to start to calculate I1. I want to add resistors to simplify but none are in series or parallel. Any help would be appreciated.
Edit: Sorry it's hard to read, R1 and R3 have values of 1k Ohms and R2 is 500 Ohms.

Edit: Sorry it's hard to read, R1 and R3 have values of 1k Ohms and R2 is 500 Ohms.