You should be welcomed in a church, demons can only act as far as God allows them.

Legit Christians CANNOT be demon possesed.

Sister, I humbly say that scripture teaches that if we are born-again believers, we are not demon possessed and they cannot control us, if we do not allow it. The Bible says resist Satan by prayer and the authority of Jesus Christ, and he will have to flee from believers. Satan is going to harass people, whether in or out of church, so don't let him use this to scare you into avoiding going to church. God has not given us a spirit of fear, but of love and a sound mind. It is Satan that tries to give us fear, but we do not have to allow it. We can resist him in the name of Jesus and by his blood. Jesus is so much stronger and more powerful than Satan and he said not to forsake ourselves from assembling in church.

Oh dear one you have a mental illness and believe me this is not a slight on you.
Although ,I do not have mental illness that causes me the same level of anquish- I do suffer from a great deal of anxiety.
Keep leaning on God you will be safe in him.

Jesus wants you to be his slave.

Revelation 1:1 (HCSB)
"The revelation of Jesus Christ that God gave Him to show His slaves what must quickly take place. He sent it and signified it through His angel to His slave John,"