Okay - if you said bad things, ask God to forgive you and consider whether it would be appropriate for you to apologise on the other board for the way you reacted. That's not something we can advise you on.
There are times when I've had to walk away from a forum when things got so nasty. There are times when the following applies:
"And if any place will not welcome you or listen to you, shake the dust off your feet when you leave, as a testimony against them." Mark 6:11
The Lord will show you when this applies, if you ask Him. Be led by the Holy Spirit.
And remember to forgive yourself. We've all made mistakes in witnessing; I know I have. But if you let it hold you entrapped, then the enemy's succeeding in silencing you.
Therefore, there is now no condemnation for those who are in Christ Jesus, who do not live according to the sinful nature but according to the Spirit. Rom 8:1
Hugs,
Jules