Do you ever feel too insecure to be in a Relationship?

I have always been like this. I have dated but most of the time I stay alone because I am majorly insecure.

I believe that I am ugly and overall I have a lot of self hatred towards myself. I get worried and have thoughts running through my head that the person I am dating is talking to other girls, flirting and just downright playing me. Then I turn into a detective and try to find any speck of evidence that indicates this to be true.

I don't know how to get over this and am starting to feel like I will never date again and that I should never date again, or be close to anyone because of these feelings. I always end up pushing people away because of it and more often than not don't let guys get close to me.

Any advice would be greatly appreciated. Thankyou very much :}