Losing Friends in Your 30s

I have been really surprised and hurt by losing so many friends right around the time I turned 30. I’m now 31, and I genuinely feel like I have no true friends anymore. I thought I had basically weeded out most of the unhealthy relationships in my life throughout my 20s, but I was apparently wrong. I have been deeply, deeply hurt over the past year or so by people who I believed I had a solid foundation of friendship with. Does anyone relate? If so, do you have any advice on making new friends at this age? I feel very alone and am afraid to even try to make friends at this point, as I’ve lost so much trust in people.