what do you do when you're feeling insecure or depressed?

I've been struggling with depression for the last few weeks and lately felt really insecure about my looks and body. I keep comparing myself to other women and thinking "my boyfriend would much rather be with her over me" which I know is so unhealthy and not even true. I kind of got sent into a spiral yesterday when I saw that he had watched porn at some point on the ps4. I don't know why I got so upset about it. I watch porn too occasionally and I understand that it doesn't mean anything and that he's not actually lusting after the women in it. But it just made me feel even worse about myself and I started getting paranoid that he watches it secretly after I go to bed instead of wanting sex with me (even though we have plenty of sex). What can I do? I hate feeling this way and my boyfriend wants to help but he doesn't know how. I need to see my therapist but what can I do in my daily life to start loving myself more? I was confident just a few months ago so I have no clue what happened.